If these positive things are made public that will encourage other people too and the wrong perceptions will also change.
But it will create some chaos into his PM,people will start PMing him about to review their tags and convincing them to remove it which may kill DT members time.
What can be done is make a thread here for the people who want their tag to be reviewed again.
That won't help either because then everyone would spam the thread to review their tags.
There could be an automated system whereby a button appears in front of the tag after certain time period (e.g 3 months) and a request can be sent to the person who gave the tag to be reviewed. If he request is declined the next and final review button will appear after 6 months. Something like this will prevent the spam and also help those who want to improve themselves.
Self Moderated thread could be an option but other thing you mentioned looks too much importance to be given for the scammers who are supposed to get red tag for any reason.