Sorry if this was already mentioned, but how can one view a copy of the screenplay? I agree, I'm a bit on the fence about a Jim Henson biopic. It doesn't mean that it couldn't be done, but the numbe of amazingly BAD biopics greatly outnumber the outstanding ones. (I LOVED Frida, but not everyone is Julie Taymor - if the project were in her hands, for example, I'd feel a lot more confident, though even she isn't without some flaws in some of her works)
But in the end, a well-written script is absolutely essential. Which is why I am curious to view a draft, if that's even possible.