
I might have to agree on you on that. I think Sweet Mask could be the hero version of Garou. I mean, both are out of place in both groups. Garou has a sense of justice while Sweet Mask just kills and kills. I don’t really know if Sweet Mask means well at this point, if he were a true hero, he would’ve saved those soldiers. They were civilians too dammit.

Sweet Mask is a violent, unstable fanatic. In his mind, I think, they had "allowed" themselves to fall under the control of the monsters, which he considers to be the same as joining them.
He's fucking crazy, if you didn't already realize. At the meeting before this mission, he was about three snarky comments away from trying to murder Zombieman just because his biology is unusual for a human so he MIGHT be a monster.
However, I do agree that he and Garou almost seem like each other's contrapositives. I hadn't considered that angle before, but I rather like it.

Remember the alien ship scene where he just arrived too late to do anything, then yelled at all the S-Classes for being so incompetent as to not stop it in time... called Genos a disappointment, even though he didn't get there in time to stop it either... and his excuse was even dumber... he was doing stupid idol shit. He went so far as to imply that he was more powerful (or at least more competent) than Tatsumaki, which is just ridiculous.
Also, at the superficial level, his body proportions make me a little uncomfortable, but that's just me.
The mouth was such a boner-killer, I could understand Sweet Mask killing her but Those hypnotized soldiers weren’t even monsters and he dismembered them. (⊙…⊙ )