The species is listed as endangered in several states including Michigan isn't it? or at least it used to be? I've heard numerous posts to that affect, or posts stating they couldn't touch them due to them being protected.

I also don't see the point in trying to "rescue" a snake that obviously survived the trauma and was in the process of healing on it's own. Don't get me wrong, I know you're well intentioned, but I still think the snake was probably going to be just fine left alone.