Yeah but TED talks are _heavily_ edited from how they appear live on stage. TED puts an insane amount of effort into making the talks appear fluid and this is subconsciously I think partly why TED has been successful (everyone seems inhumanely perfect and articulate). If a TED talk bombs, it can be tricky to edit it into a coherent whole - I can imagine this is doubly hard with a comedian because timing is so important.
Source: I bombed a TED talk at TED 2011 in long beach. But I'm only 22 so hopefully I'll have a chance to do it again right in the future :)