I think there's a certain bunker mentality among artists - be they Hollywood writer/directors or Tokyo manga authors and illustrators - that compel them to show a certain degree of solidarity regardless of how awful the people they're defending are. And that's in no small part because the production companies and corporate suits have them under siege, doing insane amounts of work for mediocre pay, in an industry where being a pervert is considered a fringe benefit.

You see it with politicians, too. "They're all out to get us" combined with "If I don't get to be a freak, why would I even keep doing this thankless job?" Leads to some perverse social incentives.