You are just feeding the troll. And as far as this persons IP being blocked, that is what proxy is for a person can not be stopped from making accounts, you are practically begging a person to hop on a proxy and have fun messing with you by your reactions.
Calm down, toughen up, ignore them do not threaten them.
The user Windows-7_IDIOT is definitely a sockpuppet of someone on my blocked users list. Can staff please close his accounts and/or block his IP?
On a broader note, can people not create sockpuppets to annoy me? If you do, it's a violation of the TOS, and your public IP (the one visible to the entire Internet) is likely to be blocked.