Elon seems to have felt untouchable for a long time. There is a limit to how much people will overlook in the pursuit of money but let's be real here - Disney is trying to portray itself as a family company. Basically anything that happens on Twitter at this point is pretty much not family friendly. Elon being Elon might have given Disney an easy excuse to back out of ad buys on a platform they don't see a large enough target market using.