Maybe he needs to send you a picture of him holding his driver's licenseJust FYI, even suspecting somebody is a minor is grounds for an immediate, permanent ban.
Minors being active on an 18+ website is one of the surest ways to get deplatformed without question or recourse. I will always err on the side of caution when it comes to this. It is a risk worth almost any amount of extreme, prejudicial nuking to avoid.