I'm not sure if this is even possible with the current system (and it isn't even a big deal if it's a hard no) but I thought I'd ask, are we able to reuse forum tags for forum groups from users that have been deleted/frozen/are inactive and you can rename to their name etc?

i'm pretty sure that even forum groups attached to inactive accounts remain, so it wouldn't be possible to reuse their tag because it will still be considered currently in use.

I'm pretty sure that is right on this. But it does open an interesting question to me, that is: an FG tag is a 'name' like a username or a petname. Usernames and petnames are up for grabs, if you're willing to shell out the CSC. It seems to me that even though it currently isn't possible to grab a FG name, it should be made so.