I agree to that sentiment, casino owners will look for games that have possible good access in each country that they are offering their services, in terms of cockfighting, not so many countries are allowing this gamble so it affects the interest of online gambling casino owners, limited access means limited money to flow.
While with rural community where gambling into cockfighting is common, maybe chances for local casino owners to cater the game might be introduced, not sure if how they will provide or how they will attract gamblers to bet on it.
This is true because several countries limit betting options such as cockfighting which is considered too cruel to animals and it can also be seen that not many gamblers like cockfighting because only few countries are quite popular for betting like this.
For example horse racing is only popular in a few countries and only exists on certain sites and not all big gambling sites have betting options on horse racing.
Conducting such games carries the hallmarks of cruelty. So not everyone will support such games. It can be administered temporarily in places where it is practiced according to tradition, but it is better not to encourage. But these games are difficult to add to any casino or gambling. As such cruel games are not supportable. It will not be acceptable in law either. So these games are not likely to be added to any casino or gambling platform. There are very few users who have directly enjoyed such games so we can avoid it easily. Horse racing is completely different because there is no chance of harm. It is supportable.