I made 2 points:
1. If there are things you disagree with about the TED talks, instead of getting annoyed that you're not allowed to disagree on their website, you're free to start threads here to discuss your dissenting views. Why not? I think it would make for interesting discussion!
2. The discussion of whether or not they allow dissenting discussions on TED is not relevant to this thread, so if you want to talk about that, you could start a new thread to talk about it, instead of derailing this thread.
Anyway, I agree that it's silly not to allow people to disagree with them on their website, if that's true. I dunno, I've never tried joining in the discussions there. I suppose I might be irritated if I had an important point to add and they deleted it.
However, a lot of public forums have very strict modding, so I would guess it's likely more a matter of editing your disagreement to suit the strict rules of etiquette there, than about the fact that you are disagreeing with them.
So it doesn't bother me much, because we can just discuss it here instead. Which brings us back to my previous suggestion: if you disagree with something on TED, why not start a thread here to discuss it? And if you want a more in-depth discussion about freedom of speech on TED, why not start a thread here to discuss that?