Apple has a team that will manually vet the matches, so no pineapple picture or a fuzzy forced hash collision picture will cause the authorities to be notified.

So if you're worried someone will secretly send fake CSAM hash collision images to your phone to trigger the process, the worst that will happen is that some poor sod at Apple will get mildly inconvenienced.

If they know this attack is possible, Apple, not being idiots, will cover their asses in court by saying that a match is merely strong evidence that the user may have had CSAM on their account, but that it cannot be said for certain unless the full image is obtained by the authorities, and that the full image should be where they say it is, with the voucher made by the device.

Because of that, prosecutors are unlikely to want to move forward without better evidence: Apple may very well testify for the defence if they do, and judges will ultimately chew them out. So yeah, I suppose rashness and incompetence in some parties may lead to a very uncomfortable situation, but ultimately it is likely that the police would be reprimanded for it and that it would be a lot more cautious afterwards.