In a game last night I had enough inducements to hire a human blitzer mercenary for my rainbow team. As my team already has 2 human blitzers this broke the racial limits, but still was allowed by the game.
So, my question is: should the racial limits still apply when hiring mercenaries (positional limits still do - I couldn't get myself a third wardancer, for example)? If so then this is a bug in the game engine - if not then Reed's list of unwritten rules needs an update