First off, where in Afghanistan was Bergdahl stationed when he was abducted? There seems to be an assumption that he was stationed in a war zone where his base was the only safe place for Americans and that only a deserter would leave the base.
Leaving a base doesn't make one a deserter. It doesn't even make him AWOL unless he fails to show up for his next shift (and he reportedly left the base after completion of a duty shift).
Leaving his weapons only means he didn't leave the base expecting trouble. Presumably, he wouldn't have left the base if he thought he would be abducted.
Secondly, how hard is it to get off base? Is this base in enemy territory, so guards patrol the perimeter? Guards that Bergdahl had to evade to sneak off of the base? Or did Bergdahl just walk out of the main gate - an action the gate guards didn't find the least bit unusual?
If it was normal to leave the base, were there off limits establishments and/or off limits areas of town? Places where an American would be taking their life in their own hands if they visited? Was Bergdahl in one of those establishments or parts of town when he was abducted? Or was he the exception that was abducted in one of the safe parts of town?
He reportedly left the base with three Afghans. Americans at some locations (
Camp Harriman/Forward Operating Base Orgun-E, for example), have an excellent relationship with Afghans that work on the base and with the Afghans in the surrounding community. Not that Camp Harriman is particularly relevant since we don't know where Bergdahl was abducted from.
So, was he leaving with them because he was defecting? Was he leaving to go get drunk with them? Was leaving the base with Afghans that lived in the community dangerous? Or was it a lot safer than wandering around a foreign community on your own?
There's just about no info on Bergdahl's capture other than that he definitely is in Taliban hands and that he definitely is a US soldier. Those are the only two things that are definitely fact.
I'm not sure what's served by speculating on how we should handle him if he's a deserter or if he's a hero on a secret mission, since there's no reason to believe he's either.