Last I checked marijuana is federally illegal, but states can legalize it. And for states that haven't legalized it, I can promise you are not charging the vast majority of possession crimes federally. The Magistrate in Missoula or Billings would kick the BLM attorney out of their courtroom if they decided to waste their time bring a corner-crossing case to their attention because as the @Hunting Wife said, it's strictly a CYA.Have fun telling the BLM agent your interpretation. It is not theirs. Call them as I have, corner hopping is Illegal and can be cited.
If you've talked to a BLM rep on the matter, I'd be curious as to who that was and at what state/office they work out of.