someone with a developmental disability in which they mentally remain very much a child for their whole life

Adults with down syndrome are not “mentally children”. Some people with down syndrome are able to live and function independently, and even among those who don’t, they are disabled adults with higher support needs, not children. Being disabled doesn’t stop time from passing, disabled people still fucking age.

and you know what else? People with down syndrome are perfectly capable of having consensual sex. Because they’re grown fucking adults who can think for themselves. To declare them children does them a disservice and robs them of their autonomy