Well have you read them, they are dodgy I just can't see how you would joke like that. Maybe some do. Anyway as someone said, Disney being very children orientated I guess they thought nip it in the bud asap to prevent potential firestorm and loss of income.
Was it actually Disney that made the call? That surprises me in some way. Although Disney have a family friendly image to protect, Marvel studios is pretty much run independently of Disney and Kevin Feige is the primary decision maker.
The tweets were pretty bad and it does go beyond what is acceptable. However it was quite a long time ago and I would be surprised Disney didn't act sooner if they had a real problem with it considering the time he had to make 2 successful movies for them. Coincidentally he had been very vocal towards Trump and it wasnt until conservative pundits had raised the issue to Disney that it became a problem. He did have dirt to dig up but I feel it was more politically motivated than the actual tweets themselves.
Marvel has always been able to manage everything to do with their movies without interference, particularly the creative choices and how they make their movies which was one of the conditions when they went to Disney. So I guess this was an exception and Marvel must have had to back this decision whether they like it or not. Shame really as JG deserved a lot of credit to helping Marvel to where they are today.