look at the story, he was arrested at the airport by mclenburg county sheriff for
underage drinking and disorderly conduct.

assuming the sheriff had jurisdiction, it’s an action by a county sheriff pursuant to state law.

I don’t get your question? The states regulate drinking ages, they regulate behaviour.

it’s usually a crime in most jurisdiction to be “disturbing the peace” or “Disorderly conduct” or “Depriving the general public of free use of the commons”. If the kid was drunk, it’s presumptive he was underage drinking.

more details may exist, such as if he was in possession of alcohol and drinking on the flight, or if air crew complained.

if you say something is unconstitutional it means :
1) The layer of government lacks that power or
2) The layer of government is depriving the people or another layer of a fundamental right.

So to give some example, the Federal Government has the right to print money and the states are prohibited to print money. So if a state were to create California Credits, and to start printing and selling them, this would be
“Unconstitutional”. however, if a person were to create Satirical Arnolds,
to present as social commentary, this would be a first amendment issue.
So a prohibition of Arnolds would be a 1st amendment violation.

So are you arguing the kid has some sort of constitutional right to get drunk?
or the states can’t regulate alcohol or behaviour?