The carnist here uses indifference as a defense for animal abuse.
If you care about morality for humans and do not care about morals for animals, then that is special pleading, and one would have to justify that to be logically consistent. So for instance, you could try (and fail) to use intelligence as the criterion.
If you claim you don't care about other people at all, then again: you care about yourself, so you would need to demonstrate that you are somehow different from other people. "But I am who I am and I'm the only person that I know is conscious" is not a defense, because 1. everyone can say the same thing, and 2. The idea that others are not conscious when they have identical brain structures to you is unfalsifiable and again, would need justification for logical consistency.
People will claim to not care but then will go on to make statements that are something along the lines of some entity "should" do some particular thing. "Our government should invest more in infrastructure", "We should replace so-and-so at the company" or even "I should go get an oil change". Any such argument then rests on just special pleading, because the use of "should" in this context indicates that you believe in acting on your value judgment that doesn't align with the state of this world. To then say you objectively don't believe in action on a giant value judgment regarding the lives of (literally) billions of land animals and almost every human on Earth is special pleading, and requires then some justification to stay logically consistent.
If you claim you don't care about logical consistency, you actually do, because you felt the need to offer "I don't care" as a reconciliation for your inaction. So deep down inside, you do care. If you truly didn't care, then you wouldn't care to even offer "I don't care" as a defense.
Also, burying your head in the sand isn't the same as actually justifying unethical behavior. That's psychopathy, not morality.