that he was lying to you. I don't know what he had to gain, but he may very well have believed it or had some guilt over his PTSD versus what he had actually been involve in. I know of no unit that would ever send a sniper out alone for months--doesn't make any sense. Most snipers travel in pairs... and most are part of a larger unit with specific tasking. So, unfortunetly I would say you were duped. One of the classic signs of an imposter are lines like "My unit was so secret it didn't exist" "My records were destroyed when I was accepted into the program" "the Army would deny I was ever in" etc--now like every good bureacracy the military loses huge chunks of information--but rarely does it lose it all.
The second part of your question is still germane. The services have no responsibility to the Vet. Once you are out you are out. The VA then takes over and they have a whole different probablem--it doesn't behoove them to help you because it costs money. That is a bit unfair to the VA, but the fact is that they have a fixed budget which is too low. I have been out six months and have yet to have my first disability hearing, never mind medical care. The unfortunate truth is, the United States bears no particular allegiance to her veterans--once you are out you are a fiscal liability...if you doubt this just look at what we did to the WWI Vets protesting for their pensions