8. Rejection of liberal democracy and attempting to rig elections in their favor. See TX gerrymandering and rampant voter suppression.
Also January 6th attempted coup.

5. Totalitarian control of media and public institutions such as legal firms and educational institutions. See CBS and Harvard University.
6. Scapegoating latino immigrants and targeting them for violence - even those who are US citizens.
7. Unprecedented cronyism and corruption

3. Overt militarism that celebrates indiscriminately bombing other countries and killing innocent civilians.
4. Suppression of dissent using both violence and threats of violence. Also includes encouraging businesses to fire employees for criticizing the government or right-wing public figures.

A few examples:
1. An authoritarian leader that is attempting to accrue all government power in a single cult of personality.
2. Extreme nationalism that punishes any critical discussion of US history that doesn't describe the United States as the greatest and most moral country in the world.

Because no one believes that he's a secret Nazi despite the tattoo, and as a veteran I know the difference between the acts of individuals in an immoral system vs individual acts outside of that system.
You may not see any distinction between the two, but you would be wrong.

What you or I think is irrelevant to the voters in Maine.
I'd rather have a flawed Democrat that fails to meet your qualifications but appeals to the majority than a perfect candidate that loses to Susan Collins.
And BTW, there will never be a perfect candidate that we agree with 100%.

None of the info in his CV mentions Blackwater, but while his military service might make a difference if he were running in Massachusetts, it's an asset for Maine. It's your choice whether you support him or not, but I have a different view as a veteran. I prefer winning over purity test politics.

I think it's a manufactured controversy generated by centrist Democrats to bring down the opponent of their preferred candidate in the primary, and most voters in Maine and elsewhere seem to view it the same way.

Is there any evidence that he shot/killed brown people while working for Blackwater?

If you want to make his working for Blackwater an issue in the primary election there's nothing preventing you from doing so, although I doubt it will gain much traction among Maine's Democrats. However, the controversy everyone is talking about isn't about that.