I think that episode hit a little too close to home for SJW's. They're used to finding completely mundane shit to complain about(see: derpy, Molestia) not having their ideology directly attacked while they're watching a show.
Also, the reason it seems like there's not as many shitstorms now is because there's not as many things to have shitstorms about. For awhile we were in the middle of Twilicorn and soon after in the middle of Equestria Girls. Nothing that significant has happened in awhile.