[chc]

I think you have it the wrong way around. It's not that this topic isn't up for public debate, but rather that the talk was part of a debate that was already highly politicized and TED doesn't want to get into that. Once the politicos see you as a good platform from which to shout their message, you will find yourself swamped by people who just want to yell party lines at each other. If you want to remain independent of party politics, you have to keep those people away.

This is also why I'm of the opinion that Internet forums which are not explicitly about politics should explicitly ban most political discussion. Otherwise the loud partisans will eventually drown out everything else. (Remember a few years ago when it came out that there was a huge conservative voting bloc on Digg downvoting anything posted by members they suspected of being liberals, even if it was non-political? You don't want those people around.)

This isn't to say that topics one party or another might happen to like better should be off-limits, but that you should be very careful when approaching those topics not to play to the political aspects of the topic. It sounds to me like this is what TED suggests as well.