Believe it or not I've seen Lauda, JollyGood and several other DT members, past and present, withdraw red tags before.
I'd like to think that one of the things that makes a good DT member is their ability to recognize when they were wrong in the past and make adjustments to their ratings accordingly. It's the "I'm still right in the face of overwhelming evidence to the contrary" position that tends to land people in trouble.
A user who at some point is not ready to reconsider any tag, negative or positive, should probably not be selected as a DT. One of the more recent examples is Timelord
in HedgeFx case, who persisted with inappropriate red tags, which resulted in his exclusion from DT.