Yeah, anything "core" related is the epitome of homo-eroticism. Especially in the live setting. Pack a bunch of sweaty, shirtless dudes into a small space while they play grabass with each other during the breakdowns and then cry during the melodic slow parts.
I do actually listen to plenty of music with harsh vocals, I just question the logic behind it being regarded as more heterosexual than music with more traditional singing.
Also I think there's a pretty strong difference in meaning between heterosexual and masculine that people are ignoring.