This for example. No, it's not illogical. If you obtain a search warrant you are effectively obtaining a legal exception to someone's constitutional rights. Consequently we take that pretty seriously, and the parameters of the search warrant (i.e. what you get to look at) must be clearly established so as to minimally impair the rights of the person who's getting searched. I.e., if someone gets a warrant to search your house for a drug lab, they do not have a right to read your personal mail that is sitting on the counter.
Not to mention, the guy's on for murder, what do disturbing images of children have to do with whether or not he killed someone? Unless they're OF the person he's accused of killing that probably isn't even a technicality. I don't know the circumstances of this incident, but wherever you have a piece of evidence, if its prejudicial effect outweighs its probative value, it MUST be excluded on basic principles. What that means is, if I am introducing evidence which is less about shedding light on the facts of a particular situation and more about casting a particular individual (i.e. the defendant) in a negative light in the hopes that the jury will have a lower opinion of him and this might lead to them convicting him (i.e. dude accused of murder exposed as being a kiddie toucher), it has to be excluded. Otherwise you get bias.
Seriously so many people like being armchair lawyers. I am not a criminal lawyer or a litigator, so I don't really know that much about those areas, and consequently I don't really pass judgment on any particular situation without knowing the specific details. If a technical rule of procedure leads to someone getting away with something, maybe, just maybe, there's some really well founded policy reason why that technical rule of procedure exists.
Anyway this thread is about suing people. Allow me to point to the one difference between the USA and most of the rest of the western world: In the USA, if you lose, you are not exposed to costs. If you sue someone in Canada and lose, you not only have to pay your own legal fees, but at least some portion of the other side's, which is a huge disincentive to suing someone unless you're confident you have a winnable case. If this rule isn't in place, people can threaten lawsuits and a cost-benefit analysis from the other side says "we'd need to pay a lawyer 50,000 bucks to defend this, so let's instead just pay 30,000 to make it go away". Want to reduce the problem by a massive margin? Loser pays winner's costs.