Couldn't you compromise and together get a storage compartment? I know I did. When we got married my DH & I got a storage spot for the stuff he wanted to keep but really didn't need constant access.
When we bought our home it went into the basement and today 100's of comic books in acid free wrap, old HS Hockey gear, a bunch old airbrush paraphernalia, sculpting tools, charcoal stuff, special pencils and toys that'll never see the light of day have dominated about 5 huge shelves in the basement, never mind the fact my dining room is now his art studio and we have another art table in my bedroom. Oh, and DVD's we only watch once, we have hundreds. Also the signed Iron Maiden jacket sleeve he got because DH airbrushed a jacket for a DF of ours in the late 80's. It'll never get onto our walls but its there safe & sound all the same.
Sure the stuff means zippo to me, but it means a whole lot to him so it stays. You seem to feel its your home and you're 'letting' him in, I bet he senses how you feel and is trying to negotiate his own place in your world together.
Trust me, there will be plenty of other boundaries to set, I wouldn't waste leverage on this issue because if you do he'll give you a harder time on the next issue 'just because'. Save the upset for the closet space, or late night friends, sharing chores or the budget... goodness knows other things will come your way soon enough. In our home whoever cares the most about xyz wins so if it's no biggie I let it slide. Good luck