He was charged with obstruction, and it was dropped, likely because they realized it would probably be tossed. The "problem" is the police cannot detain you without suspicion of a crime. You are under no legal obligation to identify yourself without that suspicion. Open-carry of a firearm is not a crime in Ohio if you obey the federal limitations, and private property laws. You cannot be charged with "Disorderly Conduct" without committing some kind of crime. Since carrying a firearm on your person in the open is generally not a crime, the officers citing of the ORC is incorrect. As such the officer has no authority to detain Mr. Call against his will, and proceeds to do just that.
I can only speculate, but if they had been posted, than he could have been, and given the situation, would have been charged. Same applies if he is asked to leave the property and he refuses. Since he was not charged for either, we can only assume that the scenarios would not apply.