BEP: Yeah, the author brings up a lot of solid points. A few things did pop into my head though.
It is my impression (not necessarily true, but this is how I view the culture) that Catholics are largely divided by gender in the clergy. So you end up with males working almost exclusively with males on an intimate basis. That would seem to aid in the creation of circumstances where homosexual behavior could happen, and if male children are involved in those situations then the private nature of those relationships can easily be taken advantage of by pedophiles.
It's not true that heterosexuals don't display a comparable obsession with little girls in their fantasies. I admit that I'm not overly familiar with gay porn so I may be overstating this, but the sexualization of female children is a huge problem in many societies. Including our own. During my own lifetime I have witnessed this trend in America. Youth worship in the media, glamorization and sexualization of prepubescent/pubescent/slightly post-pubescent females, artificial extension of adolescence (mainly for economic reasons) and the robust development of childhood as an advertising market.
Other than that, I think the reasoning is that if members of the clergy were given a healthy sexual outlet via the possibility of marriage than they would be more likely to use that outlet to relieve psychological pressure.