He goes full-on vigilante, becoming judge, jury, and executioner for every manner of low-life who was somehow lucky enough to not be snapped out existence.
Exactly how many people were killed at the end of his blade, we don’t even know.
Catching the bad guys is fine, but generally heroes are willing to put their faith in the legal system.
However, his particular reaction was perhaps a tad extreme, and certainly not heroic.