This is a damned if you do, damned if you don’t situation. Frustrating. You don’t want to deny a good faith gesture, YET you don’t know if he may be possibly using this instance to get you to change your mind about the visiting. I think you have to go with your first instinct. If you feel accomodating you could say “Thank you for taking into consideration the appropriateness of the gift. I will allow ***** to accept it. But, this does not mean I will allow you to visit with him”.
I don’t know if he is an ‘all or nothing’ kindof guy. If he is, then he may use this instance to hold over your head. You can’t really ask your son because of course…he’ll want a gift (what 10 year old wouldn’t).
Tough situation. I’m sorry. [V]