I would say that he is a fading black. Normally on liver chestnuts, their legs get lighter as you go down toward their hooves as you can see on OTTB's horse. A liver chestnut is just that, a chestnut that happens to be darker than others. I am unsure whether it is a sooty modifier that causes it or if it just happens. With both the sire and dam being black, there was only a 1 in 4 chance of a chestnut horse (if both parents are heterozygous for black). If one parent was homozygous black, then there is zero chance for a chestnut horse.