I hate when fans complain about "wrong sounding Muppets."
Remember, when recasting a character, sounding the same isn't the first requirement. If you don't get the character, it doesn't matter if your voice is a complete perfect imitation boarding on forgery. Remember, the requirements (based on observation) are personality, availability, and sounding like them at the very end. Look at how many Scooters we went through to get David Rudman, who's been doing recasts of Richard Hunt characters since before Richard died (Look at Cliff's Nightmare. David was performing Sweetums while Richard was performing a sausage sandwich).
John does sound similar enough to Jerry (he just doesn't have Jerry's signature raspy voice, neither does Matt), but darned if he didn't act like him and have amazing chemistry with Karen Prell's Red. Gobo wasn't some guy playing Gobo that wasn't Jerry... he was Gobo.
That said, if the movie even happens at this point, I'll eat my hat. And trust me... I'm in the mood to eat that hat, but that hat looks very safe.