The idea that a federal judge would approve a warrant based on a hash collision is fantasy. Assuming they even understand what a hash collision is (most will not), their first question to a prosecutor will be “have you confirmed this is illegal material?” Prosecutors are allowed to look at the original files and are expected to do so before seeking a warrant.
Law enforcement has no incentive to exonerate you, but they have tremendous incentive not to waste everyone’s time, including their own, on fake cases with little chance of conviction.
Sadly, in the US prosecutors regularly mislead the court because our adversarial system of law is seen by many to obligate them to zealously prosecute their case up to the boundary of the law. (That the prosecutor should conceal evidence, mislead, exaggerate, right up to the point where any further and their actions would be an unambiguous crime)
As a result, there have been child porn prosecutions over totally legal material rescued only by the actress in question showing up in the court. ( https://www.crimeandfederalism.com/page/61/ )
At the end of the day, Apple's decision to reprogram their customer's private property to snoop on their users private files and report on them creates a risk for those users. The risk may arguably be small, at least today. But it is a risk none the less.
We don't need trillion dollar corporations snooping on users phones like masked vigilante crime fighters. Batman is fiction, and in even the Dark Knight when he spied on everyone's phones it was clearly portrayed as an erosion of his moral character out of desperation.
Law enforcement has no incentive to exonerate you, but they have tremendous incentive not to waste everyone’s time, including their own, on fake cases with little chance of conviction.