I've received a couple comments along the lines of "the 10x engineer I know wasn't quite like you described." Or, "a 10x engineer doesn't necessarily mean an asshole."

Of course, I don't know the people you know. And of course there are good, kind engineers who accomplish a lot.

But in my experience the type of 10x engineer also correlates with toxic behaviors for a team (like being unkind, always right, and maybe condescending?)

The bigger point of the article is that "10x engineer" is a bad archetype. It's not something to strive for. I would much rather people be 1x engineers that are kind, helpful team players. Together, the team actually goes farther & as a bonus the work is more pleasant.