Honestly, 2 of those look like a bit of a stretch to me. The other one's are already banned. As for Zizihmahen, that's still extremely sad xp farming honestly... only 1523 kills and he's being fed them.
But, I do know admin's can simply take away the unit xp as well, which may have been what Joe did after banning. I don't know for sure though honestly.
And no, this is not allowed (hence they are banned). These aren't spammers for one, they're xp farms. And we explicitly say in the rules, farming xp is bannable if proven to have any connection (essentially, this is no different than before...).
But currently, it is very early morning for Joe & Alex. If it's illegally farmed, the xp will be taken away for sure and he'll likely get a ban if any connection can be found (sadly, we can't put it past players to try framing each other... because you all seriously do shady crap like that all the time too...)