Mr. Bimbo (or whatever) I think was just a gag they threw in. It was funny.
I think we can notice that during the absence of Oz, Fozzie (and the other characters) really played almost non-existent roles. For example, the short roles of Fozzie et al in MTI, MCC, and MFS (With the exception of Piggy and Animal).
MTI--Fozzie was kind of classic behavior Fozzie playing a "ROLE," so it's unfair to say Fozzie was made to be stupid here, as he was 'playing' dumb, see?
MCC, MFS--Fozzie was there only a few minutes. Why? No Oz.
Never saw any Muppets Tonight stuff, so I can't say how Fozzie was on those.
Since TMS and the first 3 Muppet movies, I think Fozzie in IAVMMCM was the most original behaving Fozzie, at least since the absence of Oz.
I'm really not that worried anymore about Frank's being gone. I think the transition has gone over smoothly (taken too long to be done) and that the characters are fairly well voiced dead-on, and will improve with time. I'm sorry Frank had to make the decisions he had to make regarding the Muppets, but to each his own.
Currently, I'm more worried about the status of Jerry Nelson's health and his characters!!