Pretty much everyone will break the law multiple times in their lifetimes. They just are not charged/convicted. If LE went over your life with a finetooth comb and they wanted to charge you with something, chances are that they would find something to charge you with.
But anyway, if LE don't have evidence of his involvement with anything criminal relating to ZB, and if he is in the US illegally, then just waive these minor charges and send him home.
What I find amusing is the presumption that this will somehow allow him to avoid justice. Has it escaped everyones notice that he might well be facing serious charges back in Australia relating to the circumstances by which ZB left in the first place?