Yeah, Moore almost certainly made that up for dramatic effect. Considering all of the possibilities for psychological scarring in his childhood and young adult life (his father dying of syphilis, his mother dying in a hospital and suffering from hysteria, the loss of his grandfather that mentored him, and his own physical and psychological issues), it is entirely possible that he never fully matured sexually.
But I don't think his sexuality was his biggest concern. If I had to guess, it was social isolation and depression. It comes out in his writing style; the first person, past tense confessional riddled with guilt.
