There has been some debate about whether, legally, Disney transportation is truly covered by the federal mandate. Universal's transpotation has dropped masking, which would suggest either (a) they are doing something illegally or (b) Disney could drop it too. Regardless, though, Disney has followed the federal mandate, and with it set to drop so soon, I doubt they have any desire to test it.
I oppose government mask mandates either way, requiring or banning masks. However, many private businesses -- including Disney -- have historically had their own rules against people covering their faces unless for a legitimate medical reason. Largely, that has been due to security. And it was always considered legal for them to do so. Until the pandemic, for example, you couldn't walk into a bank with your face covered. Disney wouldn't even let people over a certain age wear costume masks. It will be interesting to see if such businesses ever go back to those kinds of rules.