Our Confederate soldiers with families had a rough time worrying about their families back home, poor government support, bushwhackers back home, inadequate rations, clothing, pay, etc. It's amazing that so many stood up to the end. I'm not so sure that those who "deserted" were shunned post war.
In this case we have no amplifying information other than muster reports and Federal POW records which at this late date recorded many turning themselves in as "deserters."
In McCain's case, you have a wealthy 45 year old who was undoubtedly conscripted late in the war.
Did he "desert" because of a health issue? We do not know. However, this seems likely as he died shortly thereafter and was perhaps convesling somewhere.
I believe publication of such information at this late state of our Presidential campaign to be highly of a Political nature.
John McCain graduated three years behind me, and I'm in no way meaning to come to his support.
George Martin