USPS text scammers duped his wife, so he hacked their operation

I hate that it kicks off with "DISCLAIMER: This is not my work. I would never and don't condone illegal hacking of scammers"

You know what? I do. We all should. These scammers are awful people and deserve to be attacked. I am tired of toothless authorities like CISA and the alphabet agencies in the US doing next to nothing about it unless some YouTube scam baiter does the work for them. Scammers destroy people, not just financially, but emotionally as well, even driving some victims to suicide. As far as I am concerned, any wannabe hacker out there should be using these scammers for target practice.

vigilantism can spiral out of control. While it makes sense in this scenario, it's because the scammer is obviously breaking some law and is criminal. What happens if it wasn't so obvious?

If society doesn't want vigilantes than it must take an active role in pursuing and punishing criminals.

Precisely correct. People have a natural right to receive justice, so IF the government abdicates its assumed responsibility to provide justice people have every moral and ethical right to enact justice themselves.

Because the real world is a Batman comic book.