Keep in mind he was bred to sorrel mares and sorrel is dominant. But obviously he is not homozgyous for black if that is what you are wanting.
As for him not throwing color I would bet a small fortune that those red foals will test positive for Tobiano and one will test positive for LW. They are just minimally marked. But again if you are going for more 50/50 color you have to pick the right mares.
I do not know this stallion and am not recommending him. But its not fair to say he doesnt produce color when he absolutely did. And bred to the right mares he would probably throw louder color. Honestly I don't see one solid foal on there sired by him so that is pretty good percentages.
Now having said all that you should absolutely look until you find what you want and not settle for less. I do think however finding a homozygous black frame stallion for sale will take a lot of investigating and a lot of money
Just always keep in mind conformation first, color second.