That was a weird one.
I get the feeling that we were meant to be siding with Lisa but her rant seemed really off base; Bart all but worshiped Bossy Riot and was desperate to be part of their gang. Obviously he wasn't read up on feminist theory but his admiration for the older girls seemed a hundred percent genuine, even though they treated him like crap. How is he a 'mercenary' again?
The showed also forgot to make the BRAs actually villainous. I get why they why the writers would balk at Milhouse and Nelson viciously trolling female characters on the internet or indeed in school but the only thing we actually saw them do was 'hate non-watch' Itchy & Scratchy and stage a protest outside the studio. It just seems weird that we're meant to cheer at these children who were immature but didn't actually hurt anyone get their comeuppance while Bossy Riot, who committed a petty vandalism spree, tried to destroy a beloved tv show and were relentlessly mean to the adoring Bart rode off into the sunset lionised as heroines. Um, yay?