While there are some defenses to brandishing, I don't see where any of them apply. Sounds like he was being a road ragey a-hole and just assumed (correctly) that he would get away with it.
Totally agree. Then again, in my state displaying a firearm is not in and of itself a crime, and it is possible that the same is true in MN. I've been told about local cases where non-cop a-holes displayed a gun whilst road raging and the responding officers had to tell the reporting party that unless the gun was pointed at someone there was no crime and that they couldn't do anything about it.
It seems that most people are ok to some degree with the fact that cops can get away with an occasional minor infraction like speeding, but are people really ok with stuff like this?
Absolutely not. Assuming the story took place as reported, road raging - especially when making an implicit threat with a gun - is absolutely unacceptable behavior, period. Even if it isn't explicitly against the law in MN (and I don't know that for a fact), I would hope the agent's superiors get wind of this and drop the hammer on him.
As to being okay with cops getting away with speeding,
I get away with the occasional minor infraction most of the time and I'm no cop. Most of the time I don't even get pulled over for it. I'd wager the same is true for most of us.
When it comes to actual stops, while I don't have statistics in all areas, in our local county fewer than 20% of traffic stops result in a citation with the remainder being written or verbal warnings. With county deputies the number is closer to 10%. What I take from that is that cops aren't the only ones being let off. So, while I hate the culture that says cops should never write cops under any circumstances, in my area they really don't write up most of the non-cops either. If your area treats the police department as an auxiliary revenue collection agency or you break traffic laws harder than most, then I can understand why you might feel differently.