My dentist saved my tooth, but wiped my memory

The article says that psychogenic memory loss doesn't affect the ability to remember the present. However that is not always the case -- see table 2 in Serra et al (2007) where they found that short-term memory was compromised in almost 50% of patients.

Also, the death of his father was an obvious traumatic event that could have been a trigger. (I'm also curious about whether he was recently deployed in any traumatic warzones, given he was in the army).

It's a fallacy to say "There was no reason to think that there was anything wrong psychiatrically.", as these kind of psychogenic illnesses normally happen to perfectly sane and healthy people after some kind of traumatic or chronic stress.