encourage competitive play

I don't imagine the bridge 'exploit' is high on their list of things they care about. I'm sure they don't want to persist any mechanics in the game which are so obscure in their execution, but I believe their intent in limiting the number of players invited to each TB is related to World of Warcraft(EUR) having somewhat even teams to encourage competitive play.

I think it would actually be a decent mechanic to just give the bonus honor to players on each side who remain in queue for the entire match. A lot of raids do this with wait lists and dkp so it is not an entirely foreign concept to WoW.