That picture doesn't tell me anything. What do you mean "he did this?" I'm also not sure what you mean by you've played on the servers for a long time. You have about 4 and a half hours of playtime on Skial.
http://stats.skial.com/#player/tf/98236474
Also your claim that this is a large network seems dubious as well. In the past 6 months only you and the two throwaways have connected from your IP. Either it's not that big or nobody plays TF2.
You're wavering on your story. First you said it was your housemates, but the only accounts that have connected were you and two brand new throwaway accounts. If it was your housemates and they were making new accounts to play, I highly doubt they'd go straight to cheating. Also, they would have learned about the game through you and most likely you would have been instructing them on how to play and not cheat.
What seems more likely, and this is based on myself and other admin's experiences, is that someone who has put hundreds of hours into TF2 gets bored, makes an alt to screw around with cheats, gets caught, then gets blindsided when they realize they were IP banned, not just account banned.
All that aside, the fact is there is a cheater that is connecting/did connect from that IP address and to keep them from coming back and trying to cheat some more the IP has to stay banned.
