What I meant by that is:

They seem to want to enjoy a cyber-safe space where free speech is forbidden. Yet in China, they already have plenty of such websites! Why when they are living in China, can't they settle for their mission already being achieved domestically?

I suppose if they did speak up for problems that may or may not be faced by Uyghurs, other separatists, migrant workers etc, they may get into a spot of bother; but I think that will not likely be an issue because:

1.) The average SJW foreign teacher can be a weird sort. They often talk about wanting to see 'the real China,' but those man-bunned sissymen or unshaven monster women will struggle to ever be able to take their Macbooks to a Starbucks for a soy Venti sugary thing and free wifi in a Tier 88 nongtown; therefore they will usually just stick to Beijing, Shanghai etc and will probably never actually encounter the so-called 'real China' that they'd love to save from itself.

Except that is, whenever their training centre takes them all out on a minibus on that company trip to 'climb a mountain' because the boss pocketed most of the entertainment budget for themselves.

2.) The vast majority barely speak Chinese, understand anything at all about Chinese culture etc; they'd struggle to accomplish anything even if they wanted to. They might start up a yoga club to donate money to that school for those poor migrant worker kids, but they'll be completely oblivious to the fact that they're just buying the Laoban's next shiny new Merc.

3.) SJWs don't have the power to cause people trouble in China to the extent that they do back home. Chinese men aren't completely sissified yet, the women haven't been quite forcefed feminism to the same extent that Western women have; most cries about patriarchy, privilege etc will fall on deaf ears and not only due to the fact that Tim/Tina Budong and all his newbie teacher friends can't get their point across very well in a linguistic sense.

Their complaints usually won't lead to an internet 'human flesh search' because most people don't give a shit/daren't speak out anyway, companies will not fire their targets because there's no way for them to be considered to be breaking any rules. China doesn't really give such people platforms and if they did; it's doubtful that they'd let a laowai take the stand as they really fear Western interference.