Yes, but they're not appalling "because the girls are under-age and not having a good time."
They are appalling because he is part of an organization that uses extortion to control world politics, thus erasing any kind of democracy or "public good" from our world governments. This is a life-on-earth ending tragedy.
Even if the girls he used had been 21 and over, and had a great time, this crime would still be appallling. Back before homosexuality was legal and accepted, gay sex was used to the same effect, and many people would have seen "the homosexuality" as the problem, rather than the world-controlling extortion schemes that this sexual prohibition (superstition) made possible.
This is a tough one.
In principle, I agree with you.
But justice is all about striking a balance between competing rights and interests. The rights and interests of the underage girls, and their families, have been fundamentally violated. We shouldn't ignore that.
However, American systems of justice badly need to be rationalised, and held to a high standard. That means reducing our prison population down to European norms, and putting money into things that actually work.
Concerning the worst sex crimes, that also means going with what works. In the case of incorrigible offenders, that means finding a way to stop those crimes without prison. If therapy and short prison sentences don't get the person to change, then there is one thing that will work. Removing the testes of the offender.
Worst. President. Ever.