I hadn't seen the spots. That would say that he has Lp and Patn1 at play genetically. I am not as familiar with appy gene types but few spot leopard with varnish. Perhaps some of those familiar with those genes will come along.
Still thinking grey as well as several of his spots are only visible by the skin coloration.
Some horse people change their horse, they change their tack and discipline, they change their instructor; they never change themselves.