He really shouldn’t. What the guy did was still legally wrong, and he probably knew it and weighed he would rather take jail time and commit it. A less scrupulous person could do worse things, which is why those laws are in place.
If he could somehow reduce the sentence that would be great, and if that is on the table he should, but some punishment should still occur.
He’s a vigilante hero for what he did, but vigilantes are still criminals. The main issue here is that the punishment is clearly wrong, and the message is wrong, as the judge seems to think this is paramount to treason, which it isn’t.
Did you start with the original Yakuza? Kiwami has a couple things that would feel odd to a newcomer if they don’t play 0, and the only reason you’re skipping Majima Saga here until later is because you moved 0. If you start with 0 then all the context needed for Kiwami 1’s additions and Majima Saga are available.
Plus, to be fair, we have had a massive number of newcomers credit to 0. It’s probably the favorite in the series now.