Am I the only one who finds this a bit odd? I don't enjoy beer tasting, but I do enjoy wine tasting. I can't imagine planning to go to a wine tasting at a venue and then inviting someone to meet me at that venue for dinner after I'd been there 2 hours. I would either invite them to the whole 'event' if they were "wine friends" or make totally separate plans if not.
I'm trying to think how to explain how I feel. Alcohol aside, I am often busy all day and then socialising is my time to unwind with friends. After two hours of a couples dinner often the news has been exchanged, the tension of the week is long forgotten, and you're all very relaxed. Conversation may flag, be silly, light, or even intense on issues, but it is a *different mood* to the start of the evening. This plan seems to mix one couple who are at that relaxed stage with another couple at the just arriving stage and that seems a clumsy plan, to me.
On topic, though, I don't think it's actually rude, and I don't think you can say they cancelled, but I wouldn't be super thrilled unless these were very old friends who I mesh with very easily.