And for doing that he'd deserve to get a treason charge too. However, unfortunately for you, your nice little story isn't anything like what Manning actually did with these leaks.
Manning wasn't tasked to deliever a vital battle instructions or troop locations. Nor did he take any information directly to any enemy commander. Finally, the value of the information didn't change between his getting it and his handing it over.
A closer analogy would be this:
Our solider is tasked to read all of the Commander's diaries on a daily basis, then condense the information in them into a report and pass that on to the General. In the course of his duties he starts to read things he feels are wrong, some reports about soliders looting farms, shooting civilians, and also a few rather uncensored descriptions of local milita commanders and the general staff. He copies down these reports and sneaks them out to a national newspaper reporter who then prints them.
Has this soldier commited treason? He has certainly embrassed his commanding officers. He has let out information that they didn't want released, he may have even allowed that information to get into the enemies hands, though it's not likely that much use to the them, if any use at all. But in all of that there is zero evidence that he has provided any aid or comfort to the enemy. He still should be charged for the breach of confidence, but that's it.
