But that's the same for any pubescent or post-pubescent child under 16. Is it OK for any tweens or early teens to have sex under 16 because they have sex hormones going around their bodies?
I didn't say "so they should definitely have sex" did I? If they lack capacity, they can't consent and therefore the risks are too high. But there is a danger of only considering risk. Not considering the person's rights and wishes. Seeing them as a disability rather than a person, with wants, needs, desires and feelings.
Adult humans make stupid, ugly, dangerous, unhealthy choices all the time. And that is 100% their choice. It is really important not to say, "that's a terrible choice and because you have a disability I've decided you don't get to make that choice". And bear in mind that the 15 yo will be able to consent in a year. The person with LDs never gets to have a relationship. That doesn't change capacity but it changes my compassion about it.
Sometimes SWs and carers have to make choices that other people wouldn't. About money, food, exercise, alcohol and yes, sex that consider the whole person. If the person has capacity they can make the same awful decisions any adult can make.
Considering a 15 year old. A responsible 15 yo having sex with their 15 yo boyfriend, using protection, seeking and giving consent... it's not ideal but it's different to a groomed 15 yo having non consensual sex with a 45 yo.
It's so easy to look at these situations and believe there's a black and white answer. I wish there was. But it is often extremely nuanced. Confidentiality means we can't share tough cases but I know that none of the people on here could come up with flawless answers to many of these questions. Much as it's fun to assume SWs are idiots, careless, lazy and thick; most of the ones I had the privilege of working with were and are underpaid, overworked, intelligent and caring.