If this rooster has a good temperament (calm and gentle), I would just use him for breeding with your Red Sex Links. As I stated in my post, the offspring are going to be barnyard mutts anyway (even if you breed your RSLs with a standard breed rooster) and you don't want to breed aggression into...
It's a mixed breed rooster which appears to have some Speckled Sussex in it. If crossed with Red Sex Link hens (which are hybrids and don't breed true themselves) the offspring will just be barnyard mutts, although they may very well be good layers.