YES ex-cockfighting birds CAN be rehabilitated and are NOT dangerous to humans. In fact, these birds tend to be unusually more friendly towards humans because as they were used for cockfighting purposes, they were kept in isolation from other roosters and regularly handled by humans. The only potential danger they may pose is to other roosters. However, that being said, there have been instances where ex-cockfighting birds have been easily integrated into a flock with multiple roosters without any conflicts. Each bird is different.
It is quite unfortunate that there are still many people who participate in the barbaric (and also illegal) “sport” of cockfighting in the United States. They will toss roosters into a ring with razor-sharp knives or "gaffs" tied to their legs. Usually both birds die from their injuries, including the fights "winner." When cockfighting operations are busted, usually the birds (known as "gamefowl"), particularly the roosters, are euthanized because they are deemed unadoptable.
Where to Find More Information
There are many animal animal sanctuaries who specialize is rescuing roosters, particularly ex-cockfighting birds:
