Fat is not in the DSM - but - hey - why do I have belts that don't fit anymore.
Look at the debate about Lanza - he has a diagnosis of X - well, that's going away as it was found to be a distinction without use, now he will have Y.
So, if you proposed a new gun law that people with X couldn't own a gun = OOPS.
Using terms from ancient diagnostic categories or using them incorrectly, doesn't do us any good.
Antigunners propose stupid Freudian analogies on how gun folks have little ... and compensate. Cooper using a made up Freudian analogy had as much validity.
I should add that many of the foolish things said by folks like Bloomberg are part of selective information processing where you only pay attention to what confirms your beliefs. This is just normal cognition (see Kahneman) and is something everyone does across the political spectrum. I could cite blatant foolishness from left or right but won't to avoid politics. If those mechanisms are mental illness - then most people are nuts.