You never know who's going to deputize themselves as "law enforcement", with the quiet encouragement and plausible deniability of the ruling political party. Guns are unquestionably useful defensive tools against these people.
This is the actual use case. It’s a pretty established pattern of non-governmental actors like those mentioned being the tip of the authoritarian spear.
Those people should be shot in the face upon entering their first few homes or businesses, while courts and juries will still have the wherewithal to acquit anyone defending themselves.
(This is also something I was alluding to with "issuing pardons for the rebels on your side" which is already happening, of course.)
And so then it just falls back to "the good guys just need to shoot the fascist armed militia members before they shoot the good guys" which is... difficult to guarantee...
As it is, with gun ownership leaning firmly right, Trump has a massive number of armed paramilitaries that he could lean on. In any large-scale suppression of political dissent, those would be the people breaking your door at night, not uniformed feds (there simply isn't enough of the latter). Thus even if you're anti-gun in principle, it still makes sense for left-leaning people in this country to arm given the overall political climate.
There are far more people willing to defend their homes than there are people willing to get shot in the face breaking into someone's home.
We have seen what you get when you have an armed populace. Highly armed cops. Highly armed federal agents. Military equipment for civilian forces. All necessary in order to compete in the arms race against the "bad guys." All cheered for by conservatives, of course!
All that make it that much more easy to start cracking down. Maybe as a first step, issuing pardons for the rebels on your side while increasing the use of force against those protesting you.
Guns are not defensive tools. If you have a gun, but the government shoots first, you still lose.