Having been a mod at some a forum larger than TGP, it's not exactly a fun job. You might get a perk or two, but it's unpaid and enforcing someone else's rules. Usually at the expense of people you know and often like.
The large forum I volunteered at actually didn't allow any off-topic conversation. You're never a popular fellow when enforcing that. Oh, you want to talk about bird houses? Find a bird house forum. Your grandkids sure are cute, but how about you talk about that with their grandma? She died? Find a support group. Yeah.
I try to keep in mind that I'm a guest on someone else's dime. If I want to set the rules, I need to start my own forum. I can see the language thing, along with TGP's other rules, as making sense. There are enough employer and institutional content filters out there that they don't want to be blocked by. Once your site is on a block list, it's tough to get it off. That can kill a forum pretty quickly in terms of traffic.
I think my favorite thing when I was a mod were the guys who would violate the rules, then get all butt-hurt about it. No, you don't have freedom of expression here. No, I don't really care. No, it won't help you to insult me, but it will confirm what I already think. Hey, did that guy get banned because he couldn't behave? I bet he doesn't do this crap in public...
The mods are rarely the problem.