get really really enthusiastically interested in the watch. ask for details seem super impressed. massage that wealthy ego to the point of basically a blow job. but then just like keep going. see how long you can keep the topic on that one specific watch. don't ever let him talk about anything that the watch means or about the dynamic he tried to establish.
optionally, loose interest and leave without ever having let anything be said that wasn't about the watch. this is how you weaponize autism against egotists.
I can attest it's really funny. I get a sick kind of pleasure from evoking discomfort in people who don't want me to like them. I'm not really good at being nasty to people so it's something I started doing when I learned nasty people don't like it when you're nice to them or unfazed by their vampire antics.
If you've heard of "mirroring" before, that's my favorite. Mirroring people who don't like you fucks them up in ways I don't think I could with words