So basically people won't have to do this grind for getting a brahmin (Getting fibers, making rope, finding the right brahmin)
I've noticed the cow people don't have brahmins...even though they literally have some, you still can't buy them.
So I'm suggesting to make that special pen spawn Brahmins so he can sell them. Seeing how NCR is abandoned, no one sells cows to him...even in other towns.