What you are calling "political reasons" is much broader like already explained by examplens. The way of taking criticism, reacting to certain comments, being very "aggressive" to push a viewpoint, admitting mistakes etc.. If someone thinks at the same time that my way of discussing is too weak / to harsh / too whatever and they distrust me, I would have to live with that, no matter if I think this is justified or not. Of course, I could ask a question, why they did so but of course I wouldn't do that via big hammer topic in reputation.
Trust list doesn't mean trust feedback, as trust list directly means "I trust this member's judgement". 
It's even common that people get a trust list entry basically for nothing.
Or if someone just doesn't like me after a normal discussion (not politics related), they can distrust me as well.
There are simply so many reasons.
We had a certain member who was advertising gambling in his signature, while saying that gambling would be "unethical" but still, he participated in a paid gambling sig campaign.
We can distrust members who are shilling crap because we believe that they could push this crap via DT position, doesn't matter if it's a shitcoin or a shady service etc.
As already said in the topic there have even been negative trusts for shilling CSW and BSV.
Which can also be legitimate, DT can sort this out.
And if someone disagrees to someone's judgement, everyone has a possibility to add someone to their distrust list.

Regarding the negative feedback, which I've sent to digaran, that's quite simple: if there's no reason to leave a feedback or the feedback is simply a false claim, then, the feedback is not appropriate. But for this case, there have been 4 red tags already. So, if that would be trust abuse, there would be 5 people abusing trust.
For trust entries, DT trust feedback standards apply accordingly. 
As always, we have to review the context.

Regarding the removed positive feedback:
I don't owe anyone any positive trust feedback and I'm free to remove them any time. If someone disagrees with me, that I'm withdrawing my (positive or negative) trust feedbacks too often, there's a simple solution as well = anyone can distrust me.
Nowadays, nice-guy positive trust is much more of an issue, still many people don't care.

But there are no rules at all about withdrawing feedbacks.
Maybe we can define some but I think this is completely fine how it is currently as there's absolutely no issue with it. As far as I remember that happens quite often and I've also withdrawn my positive feedback on Ratomov just recently after what happened.