thank you!
However the issur of drinking wine with goyim isnt limited to makom michiraso per se, even social drinking is assur eg see bach 112 in goy’s house always assur in Jew’s house muttar only if Rov Yisroel
Though you are still right.
I did some research over Shabbos
Rambam Machalos issurus 17:10 says beferish that the issur to drink at Goy’s party applies even to yayin mevushal
The beis yosef in 112 says Rambam who goes on to say if Rov yisroel muttar, B”Y says his source is that Gemara where we see their are instances where social drinking with goyim is muttar, namely if rov yisroel. But he makes no mention of it being allowed becasue of yayin mevushal.
bottom line though is as youve said, Yayin mevushal has nothing to do with drinking with Goyim. The shach must mean exactly what you say.
thanks again.