Depends on how the foot got like that. Was it an injury, was he born with it, or did it just happen on his own while he was growing? If it was the latter, you probably don't want to breed him, because that problem is usually genetic. If he was hatched like that, it could still be genetic, but it could also be an incubation problem as well. If it was an injury, you can let him breed all he wants. That will not be passed to offspring.
It's really up to you. If you are breeding these to sell as hunting birds or show birds, then you probably don't want to breed the cock. If they are just pets for you, then you can really do whatever you want. Chances are none of his offspring will have problems, but they may still have the gene for the defect.