Either Bergdahl put American troops in more danger by deserted or he defected and helped kill them. There’s no third choice.
He put his fellow soldiers in danger when he left because there was one fewer to help each other. So by walking off, deserting, he put Americans in more danger. The difference between desertion and defection is defection helps the enemy fight and kill Americans.
If Bergdahl defected he consciously fought against Americans. Soldiers don’t do that.
Does he have an excuse? It doesn’t look like it.
Should he be judged before a trial? Yes, of course. Tha’t m=normal human behavior. Would our judgment’s be correct? Maybe. Maybe not but our judgmens, opinions really, have no impact on Bergdahl’s life.
His actions put American soldiers at risk. His actions had consequences for some soldiers who were killed as a result of his desertion.
That’s why desertion is so serious. It’s more than just breaking a promise or breaking an oath. Soldiers died. Bergdahl caused that.
How much worse is defection than desertion? Far worse but desertion is more than bad enough to warrant a death sentence. Defection means he fought against Americans.
Even though he could face a firing squad for desertion he still should answer the charge of defection.
No one can die twice so perhaps the sequence should be to answer the defection first. If he’s innocent of defection then he should be tried for desertion.
What about the idea that he may have been out of his mind before he deserted or that he repented after his desertion?
Some actions are too late to change by contrition. Some actions are beyond forgiveness. There’s no do-over for murder. It’s fatal and in the case of Bergdahl the right thing to do is subject him to a military trial, a court martial because no one can raise the dead.