It was a bit of a point of humor, and to contrast having a willing fighting force, versus a force that has no choice but to fight for you (i.e. you don't have to pay them.) But yes, I think it says something when you have troops that you can make die (re-croak?) for you, but you don't have to reward or compensate them in any way.
You'll also notice that I did give two other reasons. I could give more, but I consider those sufficient.