For one thing, it wasn't a feral cat. It was the pet of some people in the neighborhood.
Its why I keep my dogs in the yard.
When left outdoors a lot, even the sweetest pet cats have a feral nature while out and about. I had to "remove" one some years ago because it was coming into the yard (our 2.5 acres is on the small side in my area) and causing problems with the animals we kept at the time. The cat was smart (feral) enough that traps didn't work. It made me feel a bit bad, but sometimes reality suck.