Do Parents With Dementia Need a "Sexual Power of Attorney"?

Dad wants Mom to have oral sex and she is not into it at all. Is the only solution for him to relieve himself in the shower?

What does it hurt for elders in care homes to be sexually active? Is it someone elses feelings of moral judgement? There is not much in the homes that I have seen for old folks to have some pleasure. Might it not help them? Maybe they do not like bingo...