That's a tough call. I'm a softie so I would probably keep him but you have to decide what works for you. When you say he's ugly, what exactly do you mean? Do you mean he doesn't have the qualities that make a good Silkie-- good crest, Mulberry comb, blue face, comb, skin and legs, feathered feet, five toes and the right kind of feathers? If he doesn't he's probably not a good bird to breed. But if he does have those things but is just ugly then he'd probably be fine as a breeder.
I don't think he's ugly. Kind of cute. I probably wouldn't breed from him, though. Comb is way too big, tail feathers are solid, not silky, and have black on them. Plus the coloring of his comb, wattles & ear lobes are are off. However, if you got good hens with dark skin, he might be fine-- you'd have to evaluate the offspring and go from there if you choose to use him in a breeding program.
I would not breed that rooster to show quality birds either. It's fine for pet quality but even than he's got a lot of faults.
