If there was no contractual agreement over the name then it wouldn't make a difference if someone bought the company or not - you could have seen "EMTV's Muppets". I think you can safely bet your bippy though that the Henson's and Disney negotiated use of the Jim Henson name and they will not be able to call them "Disney's Muppets". Just because it's Disney doesn't mean Brian Henson wouldn't have had the same kinda clauses put in that EMTV had - like how the characters can be used and what they should be called. I'd be surprised if they also haven't negotiated access to the archives so that the Henson Legacy can use whatever footage they like and also for the Henson Company to be able to use Muppet images. I think taking Kermit away from the logo is probably just to stop people getting confused.