@Tess-And-Nathan0 I see you list a couple of private rooms in your home. So this guest thought "someone", meaning the guest in the other room, might steal from him? I guess some people might find that a concern- I've read similar things here before. I also list a private room in my home, but I only host that one room, so it's never been an issue. Any guest who's fearful of the host stealing from them shouldn't book a shared-home listing, because even if there's a lock on the guest room door, of course the host is also going to have a key to it.
I'd say if you have more than one guest room, it might be a fair idea to put locks on the doors that can be secured from the outside if that gives guests peace of mind.