My FIL collects trainsets. He spends ages in his shed with them and some are quite valuable but others are less so. I made a comment about how nice it'll be when our DCs are older to play with his trainsets and he spluttered and said not a chance. I said obv I know some are valuable but that in due course when they are older wouldn't he enjoy showing them to the children and involving them and sharing a hobby - I wasn't suggesting he leave them to run amok with valuable ones or to even play with them without supervision. He said he would be getting padlock for the door and they wouldn't be allowed close to them. He wasn't joking.
You might suggest he thinks my kids won't treat them with respect - but my dc is a baby at the moment so no reason to think he will be particularly boistrous or anything.
AIBU to think he is being a selfish bugger. My dh was allowed to play with them with my FIL when he was a kid and found it a great way of bonding with him given neither of them are particularly talkative.
I feel that I don't want to ever let my dc know they are even there if they can't even look at them, yet it is obvious there is something in granddad's shed (maybe bodies - he is a weird man!!!!) because he disappears there all the time. And tbh, I would make my dh be with them anyway because FIL is weird and I don;t think he is a bad man or would do anything, but I feel he should be kept an eye on if only because his manner often makes people want to cry.