The problem is that they repeatedly mismanaged and violated the BRs.

There’s only so many screw ups you can accept from a CA before you simply can’t trust them to do the right thing. Given that Trust is the basis of the entire CA system there isn’t really an option but to distrust the CA.

Note that multiple CAs have been distrusted in the past, and they were more or less instantaneous distrust. Symantec was a huge CA, and that got them through multiple errors that would have probably resulted in distrust for smaller CAs, and even the final distrust has had something like a years notice.