Of course your argument makes sense... I do not disagree with your logic.

I am not sure how other games work, but in ours the only people (NPCs) who are without a doubt 100% trustworthy and loyal are the ones you begin the game with. So in truth my regent is more comfortable with the 1st lvl bodyguards trainned for this purpose, over the 4th lvl Thugs hired for the job. My bodyguards are the people that I need to trust, do you really have time to be questioning their motives all the time? Later on in the game, dead bodyguards have to be replaced with hired ones. This is when we are forced to deal with the other issues.

Once again this logic is based on our game, I sure yours is differs.