Tools- I guess I'm the one that's crazy

That would tick me off.
1. You are doing him a favor by storing the stuff no matter where it is.
2. From I see he is just your SIL's boyfriend, they are not married. He is not even part of the family so you owe him nothing. I would tell him to come get it all if he wanted to whine because he cant get to the stuff that you were nice enough to store for him.