Sounds like a useful concept. I don't think this term should be used to push people who are aro because of trauma out of this community, of course. But I definitely think some sort of trauma could cause a person to stop forming romantic connections with people.
I'm willing to agree with Phoenix anyway, it's probably fairly rare. I could see trauma often leading to a situation where a person does feel romantic attraction, but is somehow terrified to act on that or even feel it.
Then again I sometimes wonder if I really am aro. Because I've never really been able to feel close to anyone, so I always wonder if it's something else that makes me aro as well.
Then again, I can't exactly call my average abandonment issues traumatic in any way.