John should not treat a person with a disability with more respect than anyone else, and constantly take his or her disability into consideration. While it is important to accommodate and support employees with disabilities, it is equally important to treat all employees with fairness and equality, without making the individual feel singled out or overly defined by their disability.
Additionally, he should ensure that he focuses on the applicant's skills, qualifications, and how they can contribute to the organization, rather than placing undue emphasis on their disability.