There is a difference between a person challenging a decision and(e.g.) someone calling Vod a pedophile and making fake reviews about him on external websites.
That sort of behaviour is extreme harassment. (and in my opinion deserves a red tag)
Vod is a DT member and a person trying to harass him would probably not effect Vods account on Bitcointalk in any way as he has the power already and just a troll or a spoken harassment would not matter much and he personally can deal with it by using ignore.
But if a normal user is harassed by a DT he just could not put the DT on ignore and post here normally as he should have got a red on his profile for an undeserved reason which just puts his account to scammer level on the forum.
This proves that normal people are more affected by the red trust fact and should be given an advantage to speak not the onces who already have the power to protect themself.
My intent is to take the list and turn it into a poll later for community voting on any subjective topics.
Yes, a Poll will surely give you a clearer view about what should be on the rules to red-tag.