What system is 
I would have to go look through their feedback and what not, but it might still be valuable enough to deserve to be included within someone's trust list. If they are aware it is a banned individual though I guess as DT-1 or even a candidate they should mirror what they agree with and then remove the banned user from their list. I'm trying to be a little more open minded to the nuances of this system, up to and including making an argument for a perma-banned user to be on DT-2... kinda felt dirty just typing that. I think I came to this thought when it was apparent that some users were deserving of a second chance when a year or two ago they would have likely never received that opportunity.
Just realized Ban's still aren't visible on a profile, it really should be stated on a profile page... but that's a different topic.