Bil does indeed have nothing to fear from Leonhardt, he's not one to do harm to someone who is unarmed without a damn good reason to. Bil has yet to provide such a reason. That doesn't mean Leonhardt trusts the man, far from it really.

"I never found such things to be helpful, though some may. Or it may get you attacked with how some feel about the Malnosso. I truly cannot understand that when cooperation in battle is going to benefit all of us far more."

Not to mention that the fact that one can get far more with being polite than making threats. People will say almost anything out of fear, even lies to please the one giving threats.