What if the state was concerned that social pressure to engage in these body modification activities would create intense social pressure resulting in 18 yr olds mutilating themselves in ways they would deeply regret. Can they ban providers from operating in their state? Or would the 14th require them to mind their own business? How about your 9th amendment views, which regardless, being vague and unusable, is therefore, well, unusable.
I hope this isn't getting personal or emotional. That would not be productive.
I take it that you are asking 3 questions:
A) Are there activities which have such severe ramifications, but people may engage in for immature reasons, that the state should raise the legal age of participation in above that of the legal age of adulthood? (There are such things which the state does outlaw for 18 year olds, such as tobacco. Alcohol is arguably different, being as the prevalence of vehicular accidents for 18-21 year olds under the influence was so rampant as to have posed a menace to society. Narcotics, particularly non deadly variants such as psychedelics and marijuana, is a totally different discussion.)
B) Are there activities that no adult in their right mind would participate in were they to appreciate the gravity of the ramifications, and as such one wishing to do so cannot be considered sane and it should be illegal to aid and facilitate anyone attempting such action? (Suicide would be the first example that comes to mind. The legality of suicide, and by extension medically assisted euthanasia, is another loaded discussion, with strong arguments on both sides. A much less loaded nanny state example would be something like juul electronic cigarettes or mandating seatbelt usage.)
C) Is the spirit of the constitution at all relevant, if something is not explicitly spelled out but strongly insinuated there? Do we go for a broad or strict constitutional interpretation?
If any of these questions were not your intention to ask, please correct me. I was trying to decipher your post, but I do not wish to put words in your mouth.
If I may, I wish you ask you just 1 simple yes or no question: Do your religious beliefs at all impact whether you think abortion should or should not be a protected right?