As far as I can see, the Reddit model is ripe for infiltration. Sub moderation works on a seniority system, so if you're willing to bide your time and wait until other people drop out, you can become "top mod". That allows you to hire and fire whatever other mods you want. So it's kind of inevitable if you have a large number of SJW mods in the mix that they will eventually take over any subs that don't try to root them out and aren't too objectionable for them to mod.