What is confounding [to me] is that a cavalry regiment was authorized to be formed at all, much less a large one.
Hindman had spent the last 6 months ruthlessly dismounting numerous mounted regiments, battalions and companies and converting them to the desparately needed infantry. Additionally, the multitude of cavalry horses represented a very real threat of eating up the countryside to the detrement of the rest of the army, and the civilian populace. And, there never seemed to be enough horses for supply wagons, ambulances, etc.
The losses to the infantry at Prarie Grove in December only served to accentuate the need for more infantry, not more cavalry.
I would imagine that the formation of this and other new cavalry regiments was not too popular with the several pre-existing cavalry regiments who had been forced to serve dismounted.