The Tokarev has approximately 560J of energy at the muzzle compared with the .45 auto's 702J but the bullet is traveling at approximately 1700fps as opposed to around a 1080fps for the .45. It doesn't make as big a hole, but the Tokarev has some serious penetration. I have read the bullet will go through a Kevlar vest and still penetrate 12” of ballistic gel.
My main point here is that the guy probably carefully chose his weapon. They are pretty expensive, the ammo almost always would have to be special ordered, and the gun is not all that common or a very popular choice. There is a good chance that the research was as simple finding out which pistol has the highest capacity magazines and will penetrate body armor. He may also have taken into consideration that the projectile would penetrate two or three people when shot into a crowd. If he just had “lost it” like the media has been trying to say; I think it is much more likely that he would have chosen a more common caliber. Going against conventional wisdom on his choice of weapon indicates to me that he chose his tool carefully. I am not sure why that assumption irritates you. I do a lot of research on all of the tools that I own as well.
Also, in several postings today, it's been pointed out that colleagues wondered why he was so obsessed about handgun skills and wondered why he had so many hours of training in same -- I hope there will soon be a news article devoted to this specific subject, why a doc is obsessed with handgun skills, a psychiatrist no less.