That’s ridicuous. David Letterman was not mocked because the rating fell (did they? I don’t even know what the ratings were. Do you?). He was mocked because he was a lousy host. And made self deprecating comments about being a lousy host for years later (not anything about the rating that I recall).
Jon Stewart will be mocked if he’s not funny. Of course if the show will be as you characterize it, he’ll be the perfect host for it. As he wouldn’t be in a year of non-political non-controversial blockbusters. As it is he’ll probably bring in more viewers, relatively speaking. Like me for example. Regardless of the fact that I like a lot of the movies nominated (and alway enjoy a good liberal love-in) I wasn’t interested till I heard he was hosting.
Beyond that it’s not like he’s looking to make this a regular gig. He wants to say he’s done it, and he’s doing it on the perfect year. You may be right about the ratings but it’s ridiculous to say it’ll be bad for Stewart (as long as he doesn’t go nuts and kill someone).
Stewart will get blamed if he’s not funny, but his lack of funniness wouldn’t hurt the ratings. It’d be the Cates’s mistake in choosing him. I’m sure Oscar ratings are on a ratings slide, since major network programming in general doesn’t get the ratings it used to, but he’s a big enough draw with a younger crowd. The slide will probably continue, but if there’s an obvious trend, he won’t be blamed for it.