alt Hacker NewsThat's a good idea. There could be two headers, the existing RTA header that adult sites use today [1] and another static header that explicitly states there shall be no adult content.
[1] - https://www.shodan.io/search?query=RTA-5042-1996-1400-1577-R... [THESE ARE ADULT SITES, NSFW]
What is adult content? I know parents who have no problem with their kids seeing porn. I know parents who give their kids a beer. I know parents who take their kids to violent movies. I used to know parents who will give their kids cigarettes. Most parents I know will disagree with their kids doing one of the above. I know songs that were played on the radio in 1960 that would not be allowed today, even though today we allow some swearing on the radio.