Could he be, of course, there is always that one-tenth of one percent chance for anything. I think the question you should be asking is, how likely is it? To that, I would answer not very...for a couple of reasons. First, the color seems a bit dark. Second, the head pattern just does not quite look right. That being said, I did produce one granite looking Sulfur-a het black eyed lucy, that seems to throw some darker babies. Take a look at Tim Baileys website. Look up the Sulfurs he has for sale for comparison, and see if he has a pic of his original Sulfur male.
Dave