I noticed too that some of his records state that he was in the 10th Infantry instead of Cavalry. Was there a Confederate 10th Kentucky Infantry? The only 10th Kentucky Infantry I've been able to find was Union.

He was transferred from Camp Douglas along with the William and Henry Ingles that you mentioned. If they took the oath of allegiance I would imagine that Ruel did too but I can't find any record of it. Here is the record where it mentions "disposition unaccounted for." He is number 9 on the list.
http://www.flickr.com/photos/25565803@N07/8066543458/sizes/l/in/photostream/

I can't find him listed on the roster in the link you provided but I find him in the Soldiers and Sailors Database as belonging to the 10th Regiment, Kentucky Cavalry.