With ears on.
To be honest, I'd like to see the no-daughters gene hack used on feral cats (not to mention rabbits, foxes etc). That would seriously minimize the cat problem here, too. It would also incidentally reduce the number of people's pet cats having girl baby cats and thus kittens. The remainder could then be adopted out and there could be limited breeding to keep up the pet cat population.
Once the no-daughter thing gets into the pet population (as it will, although mostly by human incompetence in keeping a proper eye on a 'pedigree' queen), there could end up being a pressure upon illegal kitten-farms hording 'clean' queens and possibly (or possibly not, if they're looking for return customers over ethical business) 'clean' toms, in whatever dank conditions they can get away with.
It happens at the moment, with pet-breeding, but if there's no easy home-test released so that regular householders (not dedicated pet breeders, just incidental ones - the ones that are probably considered the
problem at the moment) can't classify and monitor their accidental kittens, then Kittens Of Cats scenario might
require human intervention to mitigate. And a re-daughtering CRISPR sounds like a rather perverse answer, akin to reintroducing smallpox-resistance to the world by reinfecting people with smallpox. (If the worry is that someone
else is going to do it. And that's why they need the resistance!)
That's a thought-experiment, though, with its own issues of wrongness
(Would this thing be good or bad for the British Wildcat, I wonder. Currentlty, the danger is that hybridisation with house-/farm-cats is removing the true Wildcat line. If all half-wildcats were male, then... Yeah, they'd still be creating ¾-Wildcat 'infected' males, creating ⅞-Wildcat infected males... even as other non-wildcat infected males were still fathering from the remaining pure-blood females. Same increased (undesired) male competition for the (wanted, themselves classic wildcat) females. You might end up with 1023/1024th-wildcat (better than nothing!), but it would only be male and male-producing
whatever compatible female it lucked upon finding. No, this wouldn't be the answer to that problem. Even if it wasn't worryingly human-weaponisable by any mad person with an extremely long-term goal in mind. Or just
persuade enough people that the anti-malaria/polio/typhoid/rubella/measles/tetanus injections are stealth infertility attacks upon <insert national/ethnic/social/religious group here>... Like they already have spread such rumours in the likes of Pakistan.)