The big square in front of the congress was split at the half, the pro-choice "green" group was on one side and the pro-life "sky-blue" group was in the other side. Each group had a strong opinion, but the mobilization was quite civilized, I don't remember that anyone get hurt. Anyway, there were small kids on both sides with the handkerchief of the respective color.
Also, what is your definition of kid: 6? 12? 17?
Just imagine that the Church release a video on youtube where Santa visit a lot of children to give them presents, and in particular to a unborn children during the 8 month of pregnancy, and add to Santa a "sky-blue" handkerchief in case someone didn't notice the hidden message. Do you think it should be censored for kids?
In this case, I'd suggest the upper bound doesn't matter, as the criteria for filtering should be "a semi-unattended 5 year old could view it without concern."
All your examples are of topics where it's probably best for parents to initiate their child's education on the topic rather than Youtube randomly putting it in some kid's feed.
Kids < 4 really shouldn't have access to YouTube though.