PTSD has been cited as a fear conditioned disorder. That typically revolves around the amydala and other such areas that handle memory processing. MEG has defined PTSD as a psychological disorder that causes a biological problem within the pre-frontal cortex of the brain. What? They don't know.
But wait... there's more!
PTSD is an entity. Once you have it, it doesn't go away. Faced with another traumatic event and PTSD the entity can produce symptoms near on cue, worse than before.
What I'm saying is don't confuse each part of the picture. Trauma doesn't cause PTSD alone. There are biological factors present in combination with trauma. Terror? Absolutely fits the fear conditioning. Guilt and shame are emotions, not fear conditioned emotions at that.
There are lots and lots of studies on this, and what you read is partly true, however; I wouldn't put much stock into anything one or two studies outline. Nobody, and I mean nobody, knows exactly what PTSD is or what causes it, to date. That is empirical data to date. They have lots of guesses and theories, and some are factual at present, though the experts don't truly understand it themselves.
The brain is malleable. Proven empirical some years ago. So we know brain cells die, however; new ones are constantly created. The brain literally can repair itself. The big question many experts are asking, is why isn't the identified issue in the prefrontal cortex regenerating in lifetime PTSD persons?
I believe this is why PTSD has been moved out of anxiety disorders (fear conditioning) and into trauma disorders, so like you cited, other areas can be studied and examined. Saying that... other areas have been studied and examined for decades now, emotions, trauma types, lots of things... yet nothing is conclusive and nothing in relation to such emotion shows anything close to proof for effect towards PTSD.
But wait... there's more!
Basically, it has been stated they may never truly know what PTSD is, or what causes it, because it is impossible to measure the pre-environmental + genetic markers that attribute to getting PTSD when faced with an abnormally traumatic event.
Moral of the story.
The three main areas I just discussed, anxiety (fear conditioned disorder), trauma based disorder and environmental + genetic, all tend to contradict one another to some degree.
What you said first time was a valid opinion. Hell... it was a valid argument. Again though, mixing all those equations into PTSD the entity, suddenly things aren't so cut and dry any more.
Confused? It's why I don't debate what PTSD is... because the experts are too busy still trying to work it out... let alone exactly what causes it beyond an agreed environmental + genetic relationship, being impossible to measure.