You can't stop anyone, 13 or 30 years old, from sending posts .... but you choose how to respond.
can't read the link in UK ... but get the general idea of what he did ... seems typical Lolita stuff... and not acceptable in the west. ... definitely not saying what he did was right ... but
age at which sex is acceptable is a social construct ... it was only in 1929 that the age of marriage in England was raised to 16 - and in some countries around the world marriage at 12 - 14 years is legal, though 16 is the age in most places.
If anyone believes that 'children' do not have sexual thoughts, or indulge in sexual exploration, they should think back to their childhood ... .....