Being a 53 yo father of 3 twenty-somethings, I would probably suggest letting it go. Perhaps after saying it was a pretty pissy thing to do without at least giving you a warning (and chance to come get it)...
We are trying to jettison a lot of crap around here and I let my 25 yo talk me into keeping a few of his things for a while longer. I did warn him if/when we move it will be going bye-bye if he doesn’t take it when told...