Be careful. We recently had almost the same request (although they didn't say they were under 25). We thought it was a bit suspicious, but it was for good money, and they claimed to be "professionals". And it was our first true awakening, so we hadn't asked enough questions.
They ended up completely trashing the house, smoking heavily, and a shisha, too (expressly forbidden in our house rules) , spilling beer and alcohol all over everything... It cost us nearly 1000€ to clean it all up, and days worth of work. And Airbnb " Host guarantee", well, you can forget that.
So, if you want the booking, start asking all kinds of questions, list all of your house rules in the messaging system, and add severe penalties for violating them, and force them to expressly agree to all if it before allowing them to book.
Seriously. Better to scare them away before you get hammered. But if they're honest and legitimate, they won't be scared off.
Be careful.