> […] "Lolicon" is a Japanese word that's partly a loanword from "Lolita" in English; […]

Etymologically, it is a Japanese portmanteau derived from 'lolita complex', which is waseigo (Japanese words comprised of English words) meaning someone attracted to, or an attraction to, prepubescent girls (not boys, so it is not completely analogous to paedophile).

> So how does the author say that lolicon being acceptable is a mainstream view?

He seems to extrapolate from the acceptance of it in (large) online Japanese communities.