1miau acted in a fair and correct manner for years
That is correct, he has been a great DT member up to the point when he was debated on a political topic, he decided to do everything at his disposal to punish everyone who disagreed with him, be it the exclusion of a member he trusted for 4 years, removing a positive feedback, or giving a negative feedback.
But here's the simple truth: DT members should not let disagreements affect them when it comes to using the trust system properly--and here I'm making the assumption that the community has reached a consensus on what "proper" use of it is. From what I've read it does seem like 1miau's actions were spurred by emotion, but even if I'm correct I wouldn't say those actions rise to the level of wiping him from the DT list. I don't know where the cutoff point is for iffy behavior and calls for DT exclusion, but in my opinion it didn't reach it in this case.
I agree, I don't think he should be removed from DT just yet, his right-doings still overcome his bad, I just hope that he realizes his mistakes and refrains from doing them again, he needs to control his emotions and act like a grown-up man who can take criticism without the urge of punishing those who disagree with him.
I'd say there needs to be an established pattern of misuse of the trust system or some other major reason (like a proven scam/attempted scam/etc.).
The trust list / DT shouldn't be related only to scams, the ratings should be yes, but the trust list should be dictated by a few other factors, in fact, the trust list of the people you trust is very important, when you add someone to your trust list you are giving them more strength and visibility, their "vote" matters more with your inclusion.
if that person's trust list is based on their political point of you, then you know their judgment is bad and they shouldn't be on your trust list, just imagine someone is on DT1 with just 1 inclusion, and then suddenly due to their political views they get an exclusion from 1miau and are no longer on DT list, so now all the feedback left by that person are no longer visible just because 1miau wants everyone to agree with him on a 70-year-old conflict.
Furthermore, the fact that his exclusions are based on political disagreements, there could be times when his inclusions are also affected by the same thing, so this topic should at least serve as a warning and reminder for him and everyone else that for this trust system to work effectively, you should only include and exclude members based on your judgment of their judgment related to the trust system, not because they disagree with your points of view on something unrelated to the trust system, and the same thing applies for leaving/removing feedback.