If that is the legal requirement, then I would ask, "What crime had Grisham committed? What crime was Grisham committing? What crime was Grisham about to commit?"
I could postulate a number of potential offenses, but the one most likely to be relevant to the situation would be poaching as it hunting out of season or without proper license (since the report indicated that it was a rural area).
Regardless, the officer should have secured the firearm, had a conversation, found out nothing was going on, and then returned the firearm. And all of this would not have been an issue.