> the fact that the exercise of other Constitutional rights have long been conditional on age

Which of those are in regard to the 1st Amendment?

> This just looks like another example.

No, it doesn't.

> What is the consistent principle of law?

The 1st Amendment.

> I am having difficulty finding one that would support this ruling.

The judge stated it clearly. And if there's an inconsistency then it's other rulings that violate the 1st Amendment that aren't supported, not this one.