Greg learned CBT (Cognitive Behavioral Therapy). In CBT you learn to recognize when your ruminations and automatic thinking patterns exemplify one or more of about a dozen “cognitive distortions,” such as catastrophizing, black-and-white thinking, fortune telling, or emotional reasoning. Thinking in these ways causes depression, as well as being a symptom of depression. Breaking out of these painful distortions is a cure for depression.

I learned about CBT in the context of having exes with BPD. It's not just for depression, it is a broad therapy approach to address most personality disorders.

What Greg saw in 2013 were students justifying the suppression of speech and the punishment of dissent using the exact distortions that Greg had learned to free himself from. Students were saying that an unorthodox speaker on campus would cause severe harm to vulnerable students (catastrophizing); they were using their emotions as proof that a text should be removed from a syllabus (emotional reasoning). Greg hypothesized that if colleges supported the use of these cognitive distortions, rather than teaching students skills of critical thinking (which is basically what CBT is), then this could cause students to become depressed. Greg feared that colleges were performing reverse CBT.

I wouldn't call it "reverse CBT", I'd call it "fostering and weaponizing mental illness"

And yes, that's exactly what the Left has been doing for a long time now, but it massive accelerated in the last 10 years or so.

Why do you think the Left suddenly started CELEBRATING mental illness these past 10 years? To the point where it became a virtue signal and clout-boosting to come out and proclaim yourself to be mentally ill?

Because mental illness is the primary weapon the Left is exploiting to destroy society now.