I can't wrap my head around the whole "well, the law says that 14/15/16 year olds are ready for sex, Johnson did nothing wrong in *insert country*!"
Even if she had been (barely) over the age of consent, she would still have been a far from mature girl who hero-worshiped him, and he manipulated her in order to get sex. There was a massive power-imbalance between them, and while it might not have been a crime, he'd still be a morally bankrupt fecking creep who shouldn't be allowed near anyone under 18 (or dogs).
And then the whole "he's not a paedophile!". No, technically he's not. But he was definitely attracted to the idea of grooming an underage girl to have sex with him (given that he groomed a girl he knew was underage). And he probably still is.