There is no point blaming TJS. If TJS had withdrawn, the campaign would have been run differently. Consider that there may have been voters who would have voted for TT may have switched to TCB after hearing TJS' call for a more vocal and caring nation, but unwilling to accept TJS as president. Fact is, TCB did not deliver a strong enough message to convince voters in TJS's pool that he would not be a yes-man President. Don't ask voters to do their own research, it is up to TCB to convince the voters. As it was, he ran a campaign that was too "principled". A good honest man, but too honest to win an election like this.
The true show spoiler is Tan Kin Lian, without a doubt. If he had withdrawn, as "many" people told him to, then enough votes from his pool (just 0.4%) could have flowed to TCB, enough to tip the scales. It is very unlikely for TKL's voters to vote for TT.