Is he claiming it as his build?If not, it's not stealing.
This is why the game should have a thing that only allows people with the host's full trust to save.Seriously.
Durp..so if I take your hat, But I don't say its mine...I didn't steal it?
You're comparing a game to real life.
Think of all the people right now who are stealing your avatar by downloading it into their browser cache.
Or doing this: