I am probably not the only person on the face of the earth that feels that twenty year olds are not operating at the same level of maturity and responsibility as older adults. The American Academy of Pediatrics will confirm this view with a simple Google search confirming that brain function is still developing in early twenties much more similar to teens than to older adults. Look at accident statistics, actuarial science, or any host of other readily available data to confirm that twenty year olds do not operate as a group as cautiously and thoughtfully as older folks.
Calling them "kids" was done paternally, not "infantilising" them. For what it is worth, at their age I was a veteran and squad leader in the Army, my son that age is a NCO. I have been a "bullet proof kid" and have raised the same regardles of how much I try to convince them otherwise. Many of us do not appreciate our mortality until we have put a few more years behind us. That was my only point calling this group "kids." Recognising youth for what it is is a far cry from infantilising them.
I perhaps read something into your earlier post that was not there.
I worry that the more we take away responsibility from individuals, the less they develop. Its a terrible cycle, and for me part of the irresistible draw of the sea is the ideal of an unabridgeable personal responsibility.