Is commander weight a hard matchmaking constraint or a soft one? Is it even on for Historic Brawl? I've been facing pretty much the whole gamut of commanders, from complete jank to Omnath/Baral without changing my own commander, so I just assumed the commander weight was off for historic brawl.
Soft. If you don't find an opponent immediately, the matchmaker will slowly expand its range to look for someone "good enough." And the rest of your deck still matters; a high-tier commander with a much weaker deck can still find a "good" match against a normal commander loaded up with premium cards.