I can find these people repulsive and dangerous while acknowledging that we belong to the same species. It's not something they're capable of giving away, even when they act inhumanly.
It's not like recognizing reality grants them some clemency or grace. This isn't even the point, but if anything it damns them further, because (if you believe in free will) it means they could choose to be better.
this is, in fact, about the criteria for intelligence inclusive of non-human intelligences
we can't just say 'all humans are automatically in'. if you're not going to be a bigoted piece of shit. and I think it's pretty clear there are entirely non-hypothetical non-human people. elephants, dolphins, corvids, octopi, etc. these are persons. on top of hypothetical non-human people we might make from the thought-sand or find out amongst the stars, who we should have some metric to at least indicate personhood for.
so, if the criteria isn't just "human" (which is bigoted as shit) then you need other criteria; a bar which it is at least hypothetically possible for a human to limbo under, with fascists being the world limbo champions. on purpose. intentionally. to the point insisting they are human and have all the capacities and fullness of humans (which, remember, they don't want, and are mostly upset by the existence of) seems disrespectful. they're objects. like a desk. that isn't to say you should attack them because they're objects. I am currently surrounded by objects that I would rather not see attacked. it just means there's no moral dimension to any degree of self defense, if, say; my purse tries to kill me and I need to stab it.
we can't just say 'all humans are automatically in'.
We can. Humanity and personhood can be distinct. We can just say that. For instance a brain-dead human is still a human despite lacking all self-awareness and intelligence. That's fine.
Not trying to be rude, but I'm not even sure what your point is. Denying a bigot's humanity because a cuttlefish is a person... You're making a connection somewhere that I'm just not getting.
I'm saying someone is a human being regardless of their intelligence or compassion. I think you may be going by Frank Herbert's or another's définition.
EDIT oh I just saw the last paragraph. I see now. I don't disagree that fascists are lacking in certain critical faculties or even that defending your rights with violence is wrong, but I do think it's dangerous to de-humanise others to the degree you're doing.
For one, I don't think humans who lack empathy, etc are P Zombies or anything, so they are capable of experiencing complex pain and distress. They're not things.
Secondly, they can sometimes change and "become" human through experiences. Like what about the hardcore fascist 17 year old, who already had the seeds of doubt germinating in their subconscious? Undoubtedly still dangerous, but very much a full human.