This is interesting, but then my follow up is, would it be SE+guest? UA 1k? etc etc.
If it were truly SE only I love the idea, I usually travel solo (admittedly I haven't been to YUL though so this is just hypothetical for me) so it would be cool to have a calmed down lounge.
Truth be told most times the lounges are ok, but sometimes they are just way too crowded and this would likely take care of that.
I think I'd like to see this at YYZ, like a First Class lounge but SE instead, problem is would it be domestic, intl, TB? Too bad they couldn't have a central one.