I've been to pubs where people have been singing - for money - and haven't attributed the songs they're singing to the writers of these songs. Do you think they're paying royalties while making money at pubs from it? Personally, I can't see the difference when comedian's delivery in a LARGE part of the success of the joke. Much the same as singing.
I'd have an ENTIRELY differing opinion if he profited from the jokes but really, what's he done, told a couple of jokes on a stage. Lighten, the fuck, up.