Removal of the negative feedbacks from inactive members will defeat the purpose of that system, the feedbacks serves as a warning and caution for other people that might engage the person that has the feedback in the future so the system works just fine. Of course OP would say that it's unfair because he got almost all of the DT members on his bad side not to mention that the feedback is mentioning extortion which I think is a pretty serious offense, I mean isn't that a crime irl? His case isn't definitely one of those unfair ones, DT members in my experience in the forum aren't vindictive and logical when it comes to giving someone the ever infamous red trust.
I'm not talking about removing feedbacks left by inactive members, most of it remain to be legit and valid. But there is some cases feedbacks become wrong. Let's say user receive negative trust for not returning loan. And after some time user who left him feedback dies or simply become inactive. User repays loan, but he still can't get rid of red trust. Offcourse, it would be wrong to remove all feedbacks left by inactive member or remove him from DT because all other his feebacks remains legit. For now such issue doesn't happens often, but eventually it will become more frequent.
Sometimes DT members leave negative feedbacks when they have personal war against certain member or giving relatiory feedback, but that's not one of these cases. It's not that OP didn't deserved all feedbacks he got.