Complex sentence: He is affected with arthrogryposis, which impairs, since his birth, his physical ability of movement; he advocates the right to an active sexual life for people with disabilities, even if this means paying for sex.
Split into simpler sentences: He is affected with arthrogryposis, which impairs, since his birth, his physical ability of movement. He advocates the right to an active sexual life for people with disabilities, even if this means paying for sex.