It's not about trustworthiness at all. As a commish, and also a competitor in the league, I don't want to even tempt the mere shadow of a doubtful thought in the event that I win a guy for a $27 bid over someone's $26 bid. No, I've never given anyone a reason to doubt my integrity. But why even let the possibility exist in anyone's mind? It's nonsensical to leave this setting off. Just make everyone feel better (including yourself) and do the right thing.
I can count on one hand the number of times I've had to mess with the setting to get my commish on in-season, and I've commished a couple dynasty leagues on MFL for 5+ years now. It's not a major inconvenience to be locked out as commish, period. Anyone arguing otherwise is either lazy, secretly cheating, or so thin-skinned and power-hungry that the mere mention of the setting being a concern offends them and makes them want to keep it wrong even more to be in control.
Every negative commish response posted in here is sad and complete bull####.