If the reports about her father being an "Indian" is true, and it is recorded in her birth cert and his IC that he is an "Indian", I have no doubts her IC would reflect her as being an "Indian".
In the eyes of the Malays though, "being Malay" is more of a "social "/"religious" issue than a "legal" issue of what is recorded in their ICs. As a young girl, she may like other young "Malays" who upon receiving their ICs for the first time, be puzzled as to why their ICs record them as being "Indians", etc when they have been living their lives as "Malays" all along.
The perjorative DKK / DKA (Darah Keturunan Keling / Darah Keturunan Arab) was more of an early 1940s /1950s thing. Now, a person of different ethnicity be it Chinese, Indian, Eurasian, etc is accepted to have "masuk Melayu" ("entered Malay") and hence is accepted as being a "Malay" after "complete" assimilation. This means these "masuk Melayus" have Malay names, speak Malay, marry Malays/Muslims, adopt Malay culture and customs (clothing, food, culture, etc) and most important of all, are Muslims.
I have not checked what the PE criteria for being a "Malay" is. But for all intents and purposes, Halimah is a "Malay". She fits the "social"/"religious" definition of a Malay. Most importantly, she is accepted by the Malays as being a "Malay" just as the Malays in Malaysia accept Mahatir Mohammad as a "Malay" even though his dad's ancestors were from Kerala, India; and their acceptance of Abdullah Badawi as a "Malay" even though his grandmother (maternal) was a Hainanese Chinese.
Well, you are going down a very slippery slope here when you include religion in the definition of an ethnic race. The amendments to the elected Presidency clearly say that it has to come from whatever ethnic segment of the country whose turn it is to contribute a president. Not the religious segment. The presumption here is that the vast majority of Malays are muslims, but there is a minority that are non practicing. The criteria does not say the candidate must be Malay and a Muslim. If the next round of PE candidates have to be from the Chinese segment, then do they have to be Buddhist too? Many chinese are Christians. What if its the turn for an Indian candidate? Must the candidate be Hindu? Even though many Indians are Sikhs and Christians? This is why they did not add the religion element here. And for the purpose of our discourse, the religious element has to be left out too.
If you therefore disregard Humplimah's religion, which you must, then you boil it down to just ethnicity, which is what the PEC says the overiding criteria for the next President must be. In this case, is she Indian or Malay? If her father is Indian, then her IC should say she is Indian too. Therefore, she cannot meet the PEC criteria. And cannot be the next President. I give you the case of Vivian Balakrishnan. Is he Indian or Chinese? His father was Indian, and his mother is Chinese. Would anyone in SIngapore identify him as a chinese? I don't think anyone would call him chinese. Because he follows his father's ethnicity on his IC. If his father was Chinese and his mother was Indian, and he had a chinese surname, even then, i don't think people would call him Chinese. But look further at Vivian. He marries a Chinese lady, speaks chinese, lives like a chinese, eats chinese food, but would you still call him chinese? I think not. Now what about his kids? They are 3/4 chinese, but they don't look like chinese at all. They are dark skin and have different features, no one meeting his kids would ever think they were chinese, even though they are 75%. Just like Vivian is not identified with his mother's ethnic background, Humplimah also cannot be identified with her mother's background.
Now lets look at Yaacob Ibrahim. He married a Puerto Rican. His kids are raised in the muslim faith, I am sure they are immersed and grew up in the malay culture, I am sure they speak malay, etc. But if you saw them, would you call them malays? I think not. Lets not forget too the Nonya culture, which were basically inter marriages between Chinese and Malays. Obviously, the malays that married these chinese and became Nonyas were not Muslims. Otherwise babi pongteh would not be a Nonya dish. There is some small precedent therefore, that not all Malays were muslims, just like not all Arabs are Muslims.
Look at this as not just an exercise in trying to satisfy the PEC requirements and criteria. Instead, look at it from my viewpoint.
Which is: The PAP is so fucked up and so out of touch that it passes a law amending the Presidential criteria that favours it, but belatedly finds out that all its top so call malay candidates are not malays at all. How stupid can you be? Halimah is Indian or Malay? Masagoes is Arab or Malay? Yaacob might be the only pure malay in the senior PAP ranks, but he is married to a non muslim, a catholic and his sons are dual citizens, hence making him unpalatable too. Of all the malays in singapore, they could not find one 100% true blooded malay in their party to stand for the presidency. That is pretty pathetic.
In addition, the PAP is so out of touch with reality that it fails to see that there are many interracial marriages in singapore. Indians marry Chinese. Europeans marry malay and chinese. Indians marry malays. etc. Singapore is a big melting pot. Gay Loong himself has malay blood. All that moron has to do is look around in his cabinet and MP's faces and see many mixed races like Vivian, Indranee Rajah (father Hindu, mother Chinese), etc. And in the future, singaporeans will be more mixed as the products of inter marriages themselves get married and reproduced. eg. Iswaran's wife is an angmo. His kids might have Indian on their IC, but what about their kids? After 50 years in power, the PAP is still carving up singapore into races, which if I recalled was what caused the riots after independence. they have failed to engender a national identity. We are all singaporeans. we are not Indian singaporeans, or Chinese singaporeans or whatever. the PAP is still playing the race card to conquer and divide. To make sure that not one ethnic race is predominantly anti PAP. This issue of the need to vary the race of the President was never even an issue. The PAP basically raised up a non issue.
Having said all this, the PAP is the PAP. If they say this Doberman is a Persian cat, the court will confirm it for them. If they say Halimah is an alien from Mars, 70% gong cheebye and the Court will agree with them. So, if they say Halimah is malay, despite all contrary evidence, then she will be made one.