Recall that this authoritarian won the popular vote ~18 months ago.

The protection is against a minority authoritarian government. If half the populace supports the guy in charge then taking up arms is effectively a declaration of civil war. That's a case of the cure being worse than the affliction.

Fast forward a year or so, suppose popularity has hit single or low double digits, imagine a blatant attempt at subverting the election process, that's where an armed populace comes in.