Disney is a machine that monetizes fandom, and Twitter is pretty good about fan communities (modulo the conversation about abuse).
The conversation about whether twitter will be successful at streaming live content is interesting, but probably just one of those things that demonstrates whether or not they have _further_ growth potential into other spaces.
Twitter is already where lots of people go to talk about sporting events, news as it's happening, shared experiences like TV watching, and so on.
To the extent to which Disney can get access to users in the throes of emotion or facilitate deeper investment in their properties is probably useful for Disney on its face, even before anything more is built on top of or into twitter.