The issue of retaliatory feedback could also be addressed by having a comment section where a person could respond to their own feedback.
Allowing retaliatory feedback in any way results in those in the DT network can engage in shady behavior and scam for amounts less than the value of the value of the person they are trading withs reputation as upon the receipt of a scam report the person reporting will expect a negative rating themselves. This is especially true considering that many disputes are not black and white.
Allowing retaliatory feedback or not, what I mean is that I've often seen people who receive feedback, mainly neutral or negative, respond to that feedback on the other person's trust page. Having a place to respond to it on your own profile, so you can dispute the claim, maybe leave a reference link with your side of the story, without having to post it on the other person's profile would be beneficial.
Yes absolutely, allowing someone to respond to allegations is the most basic ethical considerations that should be made when something is published that affects their reputation.
Until that happens, it would be more appropriate to leave a neutral rating rather than a negative. Also, many retaliatory ratings do not in any way address claim supposedly in dispute, they are more accurately described as them saying you said something bad about me, so I ruin your reputation. To be honest, giving retaliatory feedback really is evidence the person is trying to cover something up, and is very clearly evidence they are willing to cover up bad behavior in the future.