Unless my friends ask otherwise, yes. If they say ‘dress nice, we’re all wearing cummerbunds’ no problem, I’ll turn up dressed nice without a cummerbund. If they say ‘dress nice, btw restaurant rules cummerbund’, im out.

Edit: if it’s my dinner, and the restaurant does that to one of my guests, and will not accommodate them, I’m also leaving with them and taking my entire group with me.