I really think that if someone opts into being age verified as 18+ AND publicly displays it on their profile, the border around their nameplate should be red (or I suppose a selectable color per user). Otherwise it should remain the same as it is now where it's more of a faded cyan. It's just a subtle way to show that someone opted into publicly verifying being 18+, since even if you have nameplates hidden, if you bring up the launchpad so you can aim at someone with the laser you still see nameplates even if they're hidden. This solution respects people who are "age verified" and "hidden-but-verified" without bringing attention to their verification status and still highlights people who are publicly 18+.
This could also be disabled by the user, and I guess is a toss up if it should be enabled by default or a toggle, I suppose, but in my opinion it should be just on. It will help the more public worlds to identify verified adults with minimal effort, and frankly if you're making it public that you're 18+ anyway on your profile this is just removing a step to verify that for everyone.