LKY's response is an attack on the person rather than dealing with the argument. I believe that Ms Sim's response was appropriate - she asked how the information sought by LKY was relevant. But LKY brushed that aside and continued with his rubbish, as he had become known to do.
If ever one were to be faced with such attacks, a good strategy would be to:
- point out the irrelevance of the other party's response
- state that it is a diversion and that he had not dealt with your question / argument
- ask the question / put across the point again and again until you get a proper answer
- if no proper response is forthcoming, state something like 'it's clear you are more keen to score points than deal with this issue, so I do not wish to continue deliberating with you.
I once used this many years ago in a 'dialogue' with with a former minister (not LKY, though). That guy was red in the face and speechless for enough moments for everyone to know that he lost that one.