We have to be really careful in assuming that someone will commit criminal sexual behaviour without serious evidence. Also, pedophiles were often sexually abused as children and they tend to act out their own abuse on other children. If this is the case, such a person needs help as much as justified condemnation.
Mars and Venus are the sexy planets. In modern natal astrology I wouldn't read a Venus conjunct the sun as combust so much as indicating what the person identifies with, as the sun gives the sense of one's identity. It is possible that he identifies with young females in a way that isn't wholesome. (Venus rules young women, the moon rules mature women and the mother.) However Venus rules his fifth house of children.
I think the more telling parts of the chart are Mars retrograde in the 12th house. Mars retrograde people are often very tough on themselves, as all of their natural assertiveness and aggression gets turned inward. If we think of Mars as male sexuality, this energy is being turned inward on himself, in a house that deals with secrecy and even deception. I would almost read this as "guilty pleasures" of a sexual nature.
Moon square Pluto can indicate a dysfunctional relationship with the mother: do you know if this was the case?
With Saturn, Neptune, and Uranus in his 7th house, it is probably hard for this man to establish a a positive lasting relationship with a partner.
If this kind of thing happens again around this man, perhaps you could convince him that even if he's not physically harming a child, his behaviours suggest some unresolved sexual issues, and he might benefit from psychological counseling.
I'm no psychologist but I think sometimes men who need unhealthy types of thrills do escalate their behaviours. Real kids do get hurt out of child p*rn*graphy, for example, and downloading this stuff is illegal.