So it's really fake and the site is stupid...But I do like the idea of another puppet character guest starring in a Muppet Movie, like a cameo or something (and in this case, one from the setting). That happens pretty rarely and it's always kind of neat when it does, I think. It's sorta like there's a shared universe where puppet characters are all real and valid, and it's pretty cool seeing the major puppet-celebrities acknowledge the many other approaches to what they do, or shake hands with another country's own puppet stars.
....so yeah, I'd be cool with a Flat Eric appearance. (It might also be a good touch of "weird," y'know)
....Even though he freaks JimAndFrank out (sorry).