Your friend can date that person with disabilities. Are they Christians? That's the important rule no matter if the person is disabled or not. Same with race, height, short, thin or heavy, etc. The Bible only say that you are not to be unequally yoked with unbelievers. It did not say not to marry disabled! You know that we all have disabilities? All of us have that because we all fall short of glory of God. We have the sin meaning we have same disability.
I am Deaf. I have dated all kinds: Disabled (Deafies, HOH, Spinifina, wheelchair bound), race (Am White dated whites, black, mixed, Hispanics, Polyasian). Dated a six footer and the shortest 4 feet 7 inches. I have dated really heavy and skinny types.