Readers only know what you tell ‘em. Your “my kitty” is “generic feline” to others until more context is provided.
It does sound like you would keep generic feline inside, given the veterinarian consensus is reducing the number of free-ranging cats is good for cats and birds. And you go by the vet. Sensible, many would agree.
RE: “survival of the fittest” (e.g. organisms best adjusted to their environment win out, being most successful in surviving and reproducing) - want to be careful not to misapply that thinking to justify human-influenced scenarios.
The scale and impact of cats hunting in environments where they are not native is more an example of humans disrupting local ecosystems than natural selection. Arguing animals are responsible for their own survival against domesticated predators is ethically contentious. But when everything’s natural I’m with ya on the merit-based view of predation.
The randos might be less angry if you were immediately up front about extenuating circumstances. Not all of them! But doubtless some will attack an inaccurate idea of you simply having a personal preference, whereafter you’ll feel attacked for “keeping [your cat] alive.” And that’s no good! Waste of time and needless raising of blood pressure :)