It could far easier be interpreted as healing what the caster or their god perceives to be a wound, since IT'S THEM THAT DOES THE DAMN CURING.

If the caster doesnt know how Tieflings are naturally supposed to look, are they going to then heal them of their "deformities" and remove their horns? I'd very much argue the caster's intent is irrelevent. And as others have noted, there is lore of how cure wores operates to accelerate natural healing, not just reality warp into a perfect body. Splint a break and heal it, done. Cure wounds on a fresh cut, done. Cure wounds on a 10 year old scar? Thats not a wound. No effect. Otherwise no one in DnD would have any scars, even cool ones.

because disabled guy is also a prick.

You are searching hard for reasons to argue against this. Just wanting to be how you are is not being a prick.

You're in a universe of immortal gods, magic, amazing tech and telling stories. Don't you dare pretend there's any ailment that can't be healed by some random cleric of Waukeen or Kol Korran, both being deities of wealth that would approve of their priests being basically traveling salesmen, exchanging healing for money. You can cure anything for the right amount of gold, and let's not all act like we wouldn't want our walking/eyesight/hearing/whatever restored, and actively work to pay for one of these services.

By this logic, no character in DnD should ever have scars, or exist with anything but a pristine body. And yet, some of the most famous characters out there have scars and missing fingers. How odd.

Some of the traits we want to give our characters just don't translate into this magical world, and there's no ruling where a DM can still have it make sense if the cleric is in character when doing this. What you want to ask yourself before you get to this situation is, would this guy have seriously been crippled all his life and was never able to raise the few hundred gold for a healing spell?

Usually no. A few hundred gold in most settings is actually quite a large amount for a non-adventurer.

And would an adventuring party even want him on?

Because the disabled are without worth if they inconvenience the party even slightly? Nevermind that all your ranting aboht how magic could affect the body could much more cheaply and immediately apply to objects like a wheelchair, and thus make sense for them to have worked around their disability than to have afforded some of the most expensive healing that exists to treat it.

This should've been nixed at session 0 if not all players agree that this setting allows for incurable disabilities/diseases.

Yea I don't think that most see "curing my disabled friend by force" as something that session 0 would even need to touch on. Most of these spells have "willing creature" as an assumed condition.

Cause I for sure don't want a cleric in my party that "isn't allowed" to remove curses or heal. Oh, he's wheelchair-bound? The party exits the pub, you are unable to catch up to them as there are some stairs in the way. This is life without wheelchair ramps, better get used to some boring sessions ahead. Unless you wanna explore a dungeon and see if falling down stairs while stuck in a chair is gonna be easy to survive for your lvl1 wizard.

This whole paragraph again is some hateful ableist shit with 0 imagination. I'm not even going to bother listing the dozens of simple creative solutions to "omg stairs!" that escape you, and simply point out that, again, cure wounds is a low level healing spell not even a greater restoration. And long-term scars and illnesses canonically exist in DnD. So get over yourself. If the player doesnt want "cure my legs" to be their whole fucking quest, then let them have their magical wheelchair with equivalent mobility and move the fuck on.

Jesus its not even hard. "The wheels of my contraption have a minor strength buff so i can push it easily, and some years later a kind enchanter cast a permanent low grade spider climb on the wheels so i can go up stairs and uneven terrain fairly easily now. It's not strong enough to climb walls, unfortunately. But I appreciated it immensely all the same. I get around as well as most now, I suppose. Still can't see over countertops all the time though."