Releasing any invasive species into the wild is foolish.  Releasing an invasive predator is even worse.  Its prey have no natural defenses and are unaware of their habits.  This puts them at an extreme disadvantage in the food chain.  As mentioned before, cats don't just hunt to survive, they also hunt for sport.  I've had to deal with feral cats on a couple of occasions.  Like any wild animal, they are viscous, territorial and dangerous.  Feral cats aren't the same as your average house cat.  Yes, they are the same species but they're a completely different animal.  I would prefer not to have to kill them, but like Old Yeller, some times what must be done, must be done.

I challenge anyone to propose a reasonable alternative to eradication.  I know of none since these cats have no real natural habitat.  TNR is not a reasonable solution for any invasive species.  It devastates an entire ecosystem just to protect a handful of cats.  It should remain illegal.