I'm trying to understand their motive here. Letting users legally create AI generated images/videos of Disney characters is still going to be amature and overall weaken these characters exposure.
The only reasoning I can think of is that people were/will find a way regardless to make AI generated content of Disney characters and perhaps by allowing a legal path, most people will utilize that option as opposed to alternative means. And that at least allows Disney to have some quality control over it.
Either way, there is going to be a surplus of "slop" from people. I don't see any way Disney or other companies can work around that other than forcing video sites from hosting any related media. And that will always be a moving target.