If you got in the tube first he was clearly in the wrong by banning you (or anybody else who this could have happened to). Even if you were the third person he should have warned you, put you in spec, kicked, etc.. (unless he did and you left that part out).
We still need proof.
This is an actual rule. Refer to Blocking on the rules:
http://www.ibisgaming.com/forums/showthread.php?t=5831
Edit: Aco beat me to it..