That appears to be the thesis of David Masciotra’s Alternet article, “‘You’re Not The Boss of Me!’ Why Libertarianism Is a Childish Sham.”
I would offer a more thorough critique, but as Sheldon Richman has pointed out in his own refutation, like most libertarian critics, Masciotra can’t even manage to accurately define libertarianism or so much as name one major libertarian thinker. (Hint: if you think Ayn Rand was a libertarian, you’re gonna have a bad time).
Of course, Masciatra’s claim that it is childish to be opposed to authority begs the question. Is it childish to want to be in authority and tell others what to do? Is it childish to seek out that authority no matter what the cost? Is it childish to enjoy coercing others to do what you want? Is it childish to resent others who are not under your control and attempt to bring them under your authority?
If not, then how can he and others like him complain when political groups opposed to him attempt to or successfully enforce their will against him via the state if it is childish to resent authority? Or is it only childish to oppose authority when that authority is wielded by the “right” people?
I highly doubt, for example, he would call slaves attempting to flee their masters to be childish. Nor would anyone venture to call civil rights protesters at Selma in 1965 childish.
Libertarianism is not anti-authority, but authority that is coercive and aggressive in nature. Barring the relationship between parents and juvenile children, authority must be consensual, and it must be balanced with responsibility.
Perhaps that explains much about statists. To them, the state is a parent, and people are always underage children incapable of taking care of themselves.
Judging from the historical record, I can hardly think of a belief more childish than that.