I'm not sure that we can say "political correctness" is what killed those soldiers or that if Hasan were white he would have been treated differently.

Most of the Middle Eastern people I know consider themselves "white" anyway but that aside the Armed Forces aren't really getting rid of people unless they really, really have to do so. They need every man/woman they have. Moral waivers have increased because of the need for manpower.

Also there is a small but apparently growing number of white supremacist/separatist soldiers in the military, some of whom are rather open about their beliefs. Evidently it takes bad actions, not just bad thoughts to get kicked out. So that may explain why Hasan wasn't treated more harshly.

Salon Article

I do think that Hasan's powerpoint presentation and alleged contacts with Anwar al Awlaki should have raised some alarm bells but hindsight is 20/20. Someone who knew about these contacts decided that they didn't warrant further action.

Contacts

"When the snows fall and the white winds blow, the lone wolf dies but the pack survives."
Winter is Coming

Now this is the Law of the Jungle—as old and as true as the sky; And the wolf that shall keep it may prosper, but the wolf that shall break it must die.
As the creeper that girdles the tree-trunk, the Law runneth forward and back; For the strength of the Pack is the Wolf, and the strength of the Wolf is the Pack.