But they're not the only contributor, so they'd have to either get permission from everyone else or revert all their changes, which would have been a nontrivial effort.
Yeah, you're probably right. I guess my point is directed more at community developers: Don't work for free for the benefit of closed-source products. If you want to make a substantial contribution to something that's open-source under a pushover license, either make or find a copyleft fork and contribute your changes there instead.
