Here is the song they're so triggered by. It's a fucking masterpiece, and I will be sorely disappointed if it doesn't go viral from hate-publicity: https://m.youtube.com/watch?v=QSmYxKIs3PI
(Sorry about the direct YouTube link; couldn't find a single working Piped instance. What's the MO these days?)
It is very much because of gender. If you google 'bernie sanders laura jane grace' you will find nothing but outrage-farming by all the usual culprits. If a cis musician had done this a few bigots might have whined, but the right-wing outrage machine wouldn't have chosen it for their Two Minutes' Hate.
Laura probably knows they're gonna come for her anyway, might as well be aggravating about it. That feels pretty damn punk to me.
idk i feel like even if a cis white woman (a man would be normally better [for them], but in this case it's automatically ew gei) were to sing "Does your god have a big fat dick? Cause it feels like he’s fucking me" that would not go down well with especially today's emboldened christian right