The aim of the law is to coerce people into allowing police to examine their files so that they can determine whether a real crime has been committed. Now, either the files contain incriminating evidence or they do not. If they do then as Longrider puts it:
maybe he weighed up the odds and decided to take the hit for non-compliance as opposed to providing the Bill with evidence of sexual misdeeds, eh?RIPA has no coercive power over the guilty because the prison sentence for non-compliance of RIPA will always be less than for the crime he is suspected of. The innocent on the other hand can be coerced.
You might argue that without RIPA the guilty guy gets away scot-free. True, but the law fails do achieve its aim. It can, in fact, never achieve its aim. So the argument becomes akin to suggesting that we lock up all people suspected of a crime (regardless of whether we can prove they are guilty) because otherwise some guilty people will get away.