Mother-in-law Hell

I’ve been dating a very sweet guy for 2 years now. He’s been divorced for 12 years. During that time, he never dated much - was hurt very badly in the divorce. Before meeting me, he basically served as his mother’s escort - trips, shows, etc. I would describe her as a very lonely alcoholic intellectual snob with tons of money and totally wacko. He was spending every Friday, Saturday and Sunday evening with her. After meeting me, she threatened to disown him if he didn’t stop seeing me. He refused and said what will be will be - he wasn’t giving me up. He now goes out on Thursday evenings to deliver her “bubbly” that he picks up for her and maybe one night on the weekends, sometimes not at all. He likes the freedom from her. Now that you have some background, I’ll ask my question - every once in awhile, I’ll “goose” my guy. The other night, she did that to him 3 times (within a couple of minutes). I don’t know about you, but I think that’s highly inappropriate. Not that I would ever do so, but if I EVER did that to my adult son, I’d get told in a heartbeat just how inappropriate that was. Am I off base here or am I right in thinking that was totally inappropriate?