He said he knows now that he is guilty of all those things, with one exception....he did not know or even believe, that his fellow soldiers would put themselves in harms way, to rescue him or look for him...
(REMEMBER just shortly before the Army took him in, the Coast Guard, I believe, had expelled him as mentally unstable...)
He was getting ready that day that he deserted, to report officially, the wrong doings of his immediate boss and others.... his staying in the service was going to be doomed at that point in his own crazy mind...so he decided to desert instead.....
And his fellow soldiers knew he was going to turn them in...thus he imagined, they would not try to rescue him or retrieve him....
remember, this was a guy that another branch of the Service felt he was mentally unfit to serve....