That's officially Frrrrrrcccckkk
Yeah I was told by a military officer that they get honorably discharged with PTSD and put on disability if they were traumatized badly enough.
As you said, your friend needs to make their health their priority. EVEN if they're discharged for it - how useful would they be anyway if they let this progress? There have to be plenty of sources for them - unfortunately, your friend is not unique in this situation. Can they talk to their SO? Their recruiter? Can they request for a non-military medical referral? Have they mentioned suicide? (If so, call someone ASAP. The military really takes suicide risks seriously, though I don't know how it affects their record).
A diagnosis of PTSD will affect their status in the military. If it's bad enough, a medical discharge may be enforced (had this happen to a friend in the army). He needs to seek help outside of the military to at least start dealing with the issues as PTSD isn't going to simply go away. It may not be what your friend wants to have happen or go on his record, but his mental health is very important. Without the tools in his pocket to learn how to cope with the symptoms, it's only going to get worse.
I'll look into it...my dad went through almost the same things...