That's a rich question, for sure.
I might defer to Dr. Davies in terms of the capacity assessment, but I think having the capacity piece not tied exclusively to an age is giving recognition to fact that the lived experience of an individual informs their ability to understand and appreciate the question before them. In terms of social context and in terms of experience in living with an illness, all these pieces will inform and add to the maturity they may have in regard to their current context, as compared to somebody who may just be newly in a position of living with an illness.
One's social context and one's lived experience—all of those pieces—are what add to one's maturity and capacity to make a particular decision.