Reasons of red tags
1) Join and support scam projects;
Promoting a project which turns out to be scam is not worthy of a red trust (this is my opinion), except it can be proven that the user had information about the scam, or found out at a later time and did not expose the developers.
It's possible to unknowingly enter a promotion campaign for a scam project.
I believe that theres something happen in this campaign
https://bitcointalk.org/index.php?topic=5102953.0In which the participants has given 72 hours to remove their signatures or else they will be painted in red,i dont know if i missed something but this sounds as what OP says are right
In here the issue been discussed
https://bitcointalk.org/index.php?topic=5103053.msg49461648#msg49461648