Hi Nechomah – I hope it won’t embarrass you or sound patronising (you can put a Z in there if you want) but that’s really amazing of you to go and do all the research.
Your husband is correct, the Gemoro there (see Tosfos) is talking about Besar Shlomim. That said, tell him to see tur and Beis Yosef who shtell Tzu to Bossor on Shabbos which is a really interesting Tzu Shtell since Lechora they are two totally different Mitzvos (Taynug vs. Simchoh).
In Rambam shteit that “Ein Simchoh Eloh B’Bossor V’EIN SIMCHOH ELOH b’yAYIN” and the Nosei keilim go to town on what Pshat is. See Binyan tzion and Prishoh.
L’maaseh it seems the Halocho is not klohr though as you bring from the MB, people should be drinking a reviis Yayin even on Chol hamoed. maybe one can be melamud Zechus that for someone who drinking would damage, its lo goruah from any other Mitzvos assay where one doesn’t need to injure oneself to be mekayem (except 4 Kosos – see Gemoro).
Anyway, sorry, I wasn’t having a go – this is just a pet topic of mine! People quote it like you did where I am from as well and it always brings out the pedant in me.