http://store.steampowered.com/subscriber_agreement/
If I skimmed through this and am wrong please forgive me as I'm very sick. But I'm pretty sure that what this guy did was illegal. When you purchase a game from steam Valve grants you a product license that grants you unlimited playing time and full access to the game as long as you do not tamper with anything that might constitute hacking or any other illegal modification of the game. Although since it's a product license you do not actually own the game, but Valve does. Which might be why a lot of gamers don't like Steam.
Edit: I think I forgot to mention that the guy was reselling the game that wasn't legally his thereby bringing the banhammer on himself.
If I skimmed through this and am wrong please forgive me as I'm very sick. But I'm pretty sure that what this guy did was illegal. When you purchase a game from steam Valve grants you a product license that grants you unlimited playing time and full access to the game as long as you do not tamper with anything that might constitute hacking or any other illegal modification of the game. Although since it's a product license you do not actually own the game, but Valve does. Which might be why a lot of gamers don't like Steam.
Edit: I think I forgot to mention that the guy was reselling the game that wasn't legally his thereby bringing the banhammer on himself.