>>3646341That, is a question of informed consent and capacity.
JEMH_Vol7AssessingCapacitytoConsenttoSexualActivity
In my opinion, developmentally delayed people should be sexual as often as they have inclination, bearing in mind the parameters of health. These parameters include sex addiction, and other natural consequences of sex (procreation, STDs, social stigma, social roles, etc.).
At very least, there ought not be any sexual being without an extremely pleasurable mechanism to enjoy themselves, even if only alone.
https://www.youtube.com/watch?v=WMTl9GbtcCU 