LW1 - I feel your frustration, but know that it doesn’t reflect on you. It reflects on him. If people confront you about it, you can say “I wish he wouldn’t do that”. I know you care about his career, but at this point pushing will only cause him to dig in his heels.

LW3 - How can it be “reasoned or logical” to offend your coworkers? These are people you have to see and work with every day. Are you trying to make life hard for yourself?

People who are upset about “PC Halloween” in general: you have the legal right to dress up as whatever you want, which means you will not be arrested, fined, or thrown in jail. However you do not have the right to be shielded from social consequences. Other people have the right to feel offended and treat you worse as a result.