Dont forget Jerry Lee Lewis 13 year old bride...and the fact that the marriageable age for girls in many Southern states was only raised from 14 in the last couple of decades. Southerners like to be married, and girls married very young - so young that if a man waited, the older ones were all took by then and the marriageable pool was generally younger girls.
It sounds as if Moore was dating, looking for a wife, not trying to bed children (as its being made to sound now). As for the supposed 14 year old, who says she thinks that at some point she told him that she was 14 - forget her. If she ever met him at all, she never told him her real age - and in the early photo that has been published, she could easily be 17 or older (a baby slut, in other words).
Google image Brooke Shields at 12 years old in 1979 as a Calvin Klein model. Or Jodie Foster at 12, for that matter. Girls killed themselves to loon 20.