I suspect that the man might or might not be arrested. I would be stunned if he became the subject of a Federal investigation seeking to prohibit him from carrying a weapon in front of a polling station again. I would be even more stunned if the local republican party organization, which denounced the man's activities and threw him out of the party, became the subject of further Federal action seeking to enjoin it from additional poll watching activities.
Once again, by the way, this was the objective of the Federal action that the Obama administration decided not to pursue. I believe this is a pretty accurate parallel based on the videos taken at the time and the reporting at the time of the incident.