[Blink]

You can also give them time.. like 24-48 hours for linking the accounts, if they don't they will simply get kicked.

If they decide to rejoin, the same procedure again, no linking after 24-48 hours? Kick.

Linked? Then you get the "role" members or something like that on discord, and you get to stay x).

That'll require a custom bot to be up 24/7 for both the forum and Discord.

Either that, or more work for staff.