Actually a 17 year old can’t legally buy an AR-15. The age is 18 for long guns and 21 for handguns.
Rick Price

I’m surprised you don’t know that you can buy a long gun like an AR-15 or a light machine gun from an unlicensed dealer at any age. Seems like something the son of a US Marine would know. Have a look:

And if anyone has a known agenda that negatively influences their views on sexual assault, I’d avoid accusing women like Professor Ford and take a look in the mirror instead.