Much like the people who ask in the customer service forums if losing consistently is against the win trading rules....

Blizzard can't ban you for being bad at the game.

That being said, even if you WERE a bad pvp'er, nobody else in the battleground has the right to complain. You pay for your access to the BGs same as they do. Just like you can't kick a solo boxer who just plain sucks at PvP, they can't kick you.

Granted, you should try NOT to suck, but losing because you are bad at PvP doesn't mean they can retaliate in any way, shape or form. In fact, if they harass you to get you to /afk out of the BG, I believe that it could (depending on severity) be considered bannable harassment.