Christ, what assholes. I get that storage space is finite, but if a museum is dealing with these sort of donations, the absolute least they could do is ask the original donor if they have someone that can accept those donations or if they'd like them back.
One time I left a piece of hardware to be repaired at a place and if they wanted to they could have it on their exhibit space until it's done, months later I've heard they forgot it wasn't theirs and sold it. Complete asshole behaviour.
I don't think I would have been able to receive those news without getting an urge to go to their place, infiltrate the whole thing and personally extract my containers. That is to say, those really looked like really good containers on top of everything.