I think that there is a vast difference between a person insisting on their own way for an entire trip or simply refusing to wear matching shirts. I woudl nto read more into the decision other than what it is: a person who does ntoliek matching clothing. My DH hates that. WE all wore matching Lime Gree Mickey HEad shorts years ago when the DIS folks used to hand the paint chips for ID, and he did it. He hated every minute of it. I will never ask him to do that again.
I see anyone who tries to force their wants onto another as disrespectful and manipulative. I want to wear a shirt , I wear it If someone else does not that is their right. It boggles my mind that anyone feels they have the right to choose clothing for adults, and calls them childish for refusing to acquiesce.
You just cannot respect anyone elses POV can you?
OP- bring the shirt. If he wears it, fine. If not who really cares? The focus should never be about the matching clothing, hats, or anything else that is a visual that the group is a family. I think that the more you push for something the less it happens. On our last trip my nieces brought a Mickey Santa hat for all of us, red for the guys and pick for the girls. I have to say that my DH tool one look adn I saw him cringe inside. We never said a word but on our first day in the MK that man wore that silly thing all day, just like the rest of us, and we got a few nice pictures. He was once and done for most of the trip, but he dragged it along for a few family photos in front of park icons the rest of the week. For the most part, we all wore the hats (it was rainy and that thing was a great way to stay sort of dry) but had we ridiculed DH or pushed him that hat woudl have been symbolic of making him do wha the did nto want to do. Take the shirt, and say nothing.