Problem with castrating a male spraying cat is that the spray ISN'T urine... cats have these glands in their bum that they purposely burst in order to release that icky stuff. Normally I wouldn't know that but my MIL was convinced that her cat Putter's ... puts grew back after he was fixed because he wasn't a baby when they did the snipping... though, honestly I like that scenario better than self mutilation for the sake of mating. GROSS.
Problem with taking them to the pound is that because they are feral the likelihood of them being adopted is slim to none... particularly in the small window available in most places. In the meantime people who have a nice, but homeless, cat are told there's no room at the in so that cat is abandoned... to become feral. For ALL the animals in the area it's best for these to be disposed of quickly.
Someone mentioned gardens being destroyed... bad enough if you have one cat doing that, but a whole herd is really scary... particularly if you have any gardening preggers in the area... that could cause major problems.
I know none of that is the cat's fault... but it's not a brown recluses' fault that their venom causes me problems... doesn't stop me from stomping the boogers before they can do harm.
If you're okay with just pawning the problem off on your next door neighbor then do the coyote urine... if you want to actually solve the problem then you need to catch and kill, or catch and send to someone who will.