I read the issue. And I actually saw the angry tweets (and bilious Fox News opinion piece) lambasting DC for having Superman stop a mass shooting.
Which sounds insane, but the target was a group of (accused) undocumented workers, and the shooter was a white guy, with a American flag bandana, who had lost his job and was being psychically influenced to act out on his worst impulses.
This scene, it’s posited, is some sort of SJW attempt to make anti-immigration sentiment a Bad Thing, and to make illegal aliens (sort of like Supes himself) Innocent Victims who need to be protected from True Americans.
I presume the objections are to the specific motivation being played on here (“It’s impossible, even with mental influence, for a True American to be driven to murder, even by Evil Illegals Who Stole His Job!”) as opposed to a broader dissatisfaction with Superman stopping a mass slaying. I.e., the objectors would be okay if Supes stopped, say, a generic Bad Guy who was trying to kill some generic Civilians, or even an Evil BLM Antifa Islamic Assassin who was trying slay a group of Innocent White Police Officers (preferably by beheading, so we don’t get any Gun Banning Nuts pointing at this as an argument).
Most fundamentally, I think it’s just anything that portrays immigrants (possibly illegal, but the guy calling them that is a crazy) in a positive sense, or touches on animus toward them, is simply taboo to some people — and any media that does such a thing is meant as a propagandistic attack.
Which ignores, of course, Superman’s long history as a literal Social Justice Warrior, going back to his creation, and popping up at various times that were just as socially fraught as these. Perhaps it’s just more visible now because we’re so close to it.
Superman saved undocumented workers from a racist — and conservative media is mad about it
They argue that the Man of Steel has become a tool of propaganda.

I guess the angry people missed the "Gracias a Dios" line.
Or maybe they didn't.
[ redacted ]these people for taking time out from their headless chicken rodeo to call out a fictional hero for fictional heroics.
Things like this bring the supremacists out of hiding. They out themselves.
This is a Superman thing to do. Interesting timing.
It would be a rare thing for humans who completely lack empathy to read Superman.
Perhaps His dark soul comment would change a handful of hearts and minds.
I wish for something powerful enough to awaken those who do not truly think mass murder is a good idea.
How many of these haters are young men, flying on testosterone, with as yet undeveloped frontal lobes?
Just a thought ✌️