Example: if a doctor asks you about suicidal thoughts in a negative phrasing (e.g. "No thoughts of harming yourself?" or "You're not planning on doing anything silly, are you?"), then you're significantly less likely to admit to suicidal thoughts. We have clinically effective interventions for reducing suicide risk, so even very subtle stigma could cost lives by stopping people from coming forward.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5379679/

Would a student be more likely to admit to "thoughts of doing a school shooting" if school shootings weren't stigmatized? Yes, probably. Would an abuser be more likely to admit to "thoughts of beating up his wife" if domestic violence was not stigmatized? Yes, probably. But there is a very good reason why we stigmatize anti-social behaviors. They hurt other people. The stigma reinforces that message and removing the stigma hides that message. We are "the other people" and if you do that, you will hurt us too, not just yourself, so we aren't going to pretend it's okay because it isn't.

The removal of stigmatization might make it easier for us to identify people doing awful things, but just knowing about something doesn't stop them from doing awful things. You aren't fixing the problem by getting them to admit it, you're just becoming more aware of that particular person's problems while also green-lighting half a dozen other people to do the same.

Yes, I realize that removing the stigma around suicide might help that subset of the population that are already in the midst of it, but what about in five years? Ten years? What effect will that have on others?

We can't know for sure, but there is a common theme when it comes to the normalization of anti-social behavior. It helps the one, but hurts the many.

You can look those that have attempted suicide in the eye and tell them not to be ashamed, but could you preach that message to a group of bullied teenagers after seeing the results of this study?