I think, viewing the evidence as a whole, that this guy is probably guilty. Of looking at kiddie porn. Or at least "kiddie erotica". (Which is kids in clothes, but with an "emphasis" on their genital areas. Didn't even know that was a crime. But it is.)
But go ahead and read the case anyway. And see whether 95% of the evidence against him might also exist for anyone who looks at adult pornography online. And/or you.
Sometimes you can't control popups. If those things ever have illegal stuff in them, you might well be in trouble. Serious, serious trouble.