I've never called him a child abuser. He is, however, guilty of downloading or replicating child porn, which, rightly or wrongly, is an offence in the UK. He's accepted a caution for this offence and in doing so admitted his guilt.
You're quite wrong to say that I make the assumption of guilty until proven innocent. I come at this sort of thing, as with any allegation of criminal activity, with an open mind. But I found his explanation totally unconvincing, for the reasons set out by exodus. And once he accepted the caution, that confirmed his guilt for me.
He could have contested the case at court - he has the money to hire expensive lawyers. However, he obviously knew that a jury of his peers would find his explanation unconvincing and so opted for the caution, thus avoiding the risk of an actual conviction and possible jail sentence. You pays your money, you takes your choice.