Sure, more often than not, but not always. Choosing to conform to a norm would reduce diversity, choosing to maintain American society would reduce diversity, etc. Self-determination is secondary at best, so we end up having to justify things just on the basis of whether they increase or decrease diversity, not on the basis of whether they're compatible with self-determination.

And I mentioned why I think abuse, trauma, disease, and other awful shit meet the mark for diversity.

Mentally ill people definitely add diversity on the whole to society, in terms of contributions to different aspects of culture, in terms of introducing a greater range of behaviors than only mentally healthy people would, in terms of having a wider range of internal experiences than mentally healthy people - and that has nothing to do with self-determination. If anything, self-determination would get in the way of that diversity. And this all applies to trauma, specifically. It absolutely can be disabling, but I don't think disability necessarily reduces overall diversity. Almost always the opposite.