If you have content that has a matching hash value and is identical by all computational and human inspection to content that has been identified as CSAM from w

If you have content that has a matching hash value and is identical by all computational and human inspection to content that has been identified as CSAM from which the hash was generate then you have a problem. Without getting into the metaphysics of what is an image, at that point, you basically have a large collection of child porn. Your hypothetical oppressive regime has gone to a lot of trouble planting not illegal evidence on your device. It would be much more effective to just put actual child porn on your device, which you would need to have to conduct the attack in the first place.