If it turns out that the character Cooper was referring to is indeed UD, than that could be a neat use of Muppet history - Cooper's interested in the theatre...UD has long history (predating the rest of the Muppet gang) with the theatre - those initial reports of Bobin looking over Segal's script and going "this would be a good place for Uncle Deadly" now would make quite a bit of sense!
Though i think i'd like to see UD more as an "ally" as apposed to "sidekick/henchman"
Deadly feels more like a bad guy than a good guy. I always saw characters like Deadly, Crazy Harry, Behemoth, Doglion, Luncheon Monster, Big Mean Carl, Gruper, etc as being able to play bad guys in a movie or show.
I can just imagine a dramatic turn where Cooper discovers Uncle Deadly, who feels betrayed by the Muppets or something.
At first I was thinking a new henchman was created for Cooper, but it's now becoming more and more likely that Uncle Deadly is indeed the new villain. Which...by the way, how insanely crazy cool is that? UD hasnt been seen in a zillion years, kept only alive by rabid fan interest. And here he is, about to be one of the main characters of Disney's main holiday tent pole.
INSANE!