Good excuse? Cool:
1) You're leeching
2) You could be contributing to your team instead of wasting their time. Grab a pike, some rocks and try to stun, a hand axe and shield and try to break enemy shields or cover for your team. Yes, being a meat shield is still valuable because if spazzy mcpaddington swings at you instead of me trying to get the easy kill for his KDR, I get essentially a free hit on his dumb ass and can drop him. Like sacrificing a pawn for a rook/bishop/knight etc.
3) You are hurting your team because if you'd just gtfo if you're not going to try and help, the autobalancer might put someone on their team that WILL try to help.
Yup, as an admin I'll kick for this crap pretty fast if you don't knock it off after I tell you to. The reasons I just listed are more than adequate for why you're being a bastard with your ladder "art". Go to an empty server, or go to the lljk server if you have to do this stuff.
@OP: Wasn't there, but I wish I had been. It would have stopped quick before escalating to the point you say it did.