I just talked to my guy he said that in this situation he would do a few things. Firstly ban all known nicks and IPs. Change spawn point to an area that will end in certain death. Like a platform in the sky so high the fall would kill you or on a platform in the middle of a lava pool. Build a device out of redstone (like a draw bridge in the lava pool) that only mods could use to allow the player off the spawn area. Or just warp the user to a safe zone. Anyone else dies. Additionally, being that he hosts his own servers, he would change the access port and inform all the friendlies. So like instead of connecting to 127.0.0.1:70 to 127.0.0.1:200 for example. If your server is hosted through a different site you might be able to get the IP changed on it too but he wasn't for sure.
"The quieter you become, the more you are able to hear..."
"Drink all the booze, hack all the things."