Originally Posted by
Snoop Dogg
Steve thinks Frank is garbo trash, which is why Stevil giving Frank some actual approval because they both share the "peace through strength even if you do awful shit" philosophy is one of the reasons Frank joined Hydra.
Now, some people like Ed Brubaker seem to not really understand this because he read like three issues of Steranko Cap back in the day where Hydra dudes are getting blown up, but Steve (and most superheroes) understand the difference between his allies killing in an actual wartime scenario and killing gratuitously because you think you're the law. It's not even smart to show Steve himself being brutal during war because he's supposed to be super skilled and he uses a defensive weapon.
So the Punisher killing people in Civil War, the story where the sides are very much trying not to kill each other, is very villanous behavior. The Punisher is not an anti-hero who is willing to kill or seeks to kill perceived threats like he is in the Netflix show, he kills gratuitously, and that is all he does because he is a villain. Just because he happens to target criminals does not change that, it just makes it so he is useful during crisis situations, like Thanos in the 90's. Steve is not going to give Frank leeway just because they're both soldiers and view him as more moral than goofballs like the Serpent Society. He'd view him on the same level as Zemo, where maybe he can be redeemed, but he's still a problem.
He cannot be compared to current Otto, who is not even an anti-hero with a capacity for cruelty anymore. He's developed into a standard superhero with a surly and arrogant attitude.