Even if you can't get worldGuards, it's common sense to not mine something that looks like it's been built by someone. The town in the Nether has been WorldGuarded as far as it needs to protect everything, so even if you're mining right next to the town, it's fine.

The Nether got reset for the purpose of finding Quartz. There are no other towns or special builds there, so what is the point of TP options to places? All there is beyond the town is wild Nether. If you need a TP to a spot to anywhere in the Nether, then you make a /Homeset. It's also PVP enabled, so really, it's an all-out place. You risk everything going there in the first place, so there's really no need for TP options to anywhere there.

EDIT: Also... this is more of a suggestion as well, so it should be in the suggestions/bugs forum :3