I would imagine a free unsuitable rooster (not bred for it, not the right breed, not trained) would be used by cockfighting people as part of the training for their roosters? As in, some easy prey for them to practise on. I've heard of dogs being used in this way.
It's a hideous and cruel death, and I can't believe cockfighting is legal in some places.
And all the BYCers who do it (you know who you are) and who chat about raising their 'stags' and use coded words to talk about what they aren't allowed to talk about here,