Peaceful protests, even if they’re successful, have nothing to do with the discussion of “Trying to guard against tyranny by increasing private gun ownership is dumb“
But peaceful resistance (which goes beyond protests and can – depending on situation and definition – encompass everything from sabotage to strikes, espionage, boycotts and "Work to Rule") has been demonstrated to be more effective to both establish long-term democratic rule, as well as safeguard it against authoritarian rollback, when compared to violent means.
There simply is no actual argument based on historical facts that widespread civilian gun ownership is particularly effective at establishing democratic rule or deterring authoritarian tendencies. Which makes sense, because (again) guns are only good at projecting or threatening violence and authoritarian actors (in contrast to democratic ones) are quite comfortable with violence.