Anyone who starts teamkilling in own spawn (or anywhere else, intentionally) will definitely be permanently banned from my server when I get to hosting one.
"No mercy to idiots" has always been my administrative strategy, and I'll keep that up in the future as well. In my books, intentional teamkilling is the worst sort of idiocy that exists in multiplayer games, no matter what the explanation is. I would never tolerate that, and I sincerely hope that other server admins have similar attitudes.
I just prefer fair play.
"No mercy to idiots" so surely you dislike the people who refuse to play gametypes properly, im talking about people who sit at the back of spawn sniping with SMGs and Bolts. Its Bad Company 2 all over again! If there were unlimited Marksman slots everyone would be hiding in the Univermag and The Ruskie Spawn (forget the buildings name) and ignoring the capture zones.
Obviously the above example is an exaggeration and should be treated as such, but you get the idea.