If I understand you correctly, in your opinion something should be categorized as a mental disorder based on whether a behavior is potentially harmful to others?
Homosexuality, a sexual attraction that deviates from the norm - not a mental disorder because it doesn’t cause harm.
Paedophilia, a sexual attraction that deviates from the norm - is a mental disorder because it potentially causes harm.
Seems a bit arbitrary to me. Maybe I’m missing something.