So one of the users on my instance just made a good point: Tumblr chasing horny people off is probably gonna result in lots of underage people coming to Mastodon. And us #mastoadmin types should probably start adjusting out instances' terms to say something about whether or not we allow underage people, and what special rules we may have for them.
Personally my initial instinct is to say "we expect you to be legal adults, if we discover you're not then your account gets closed but we're not gonna go out of our way to look if you can do a good job of faking it". Because I was in that space as a teen a few times. But I don't wanna be running penguin.club, yknow?