My guess is that it's BECAUSE they were enemies. They know what he's capable of and wouldn't betray him. Also he was a list of the resumes with family names and stuff so there's even more incentive not too. OR BC HE DONT GIVE A FCK!
I mean may as well head hunt from the enemy so all the decent soldiers work under him instead of his enemies good way to cut back on the competition i suppose
A BLINDFOLDDDD