A 1% false positive rate is probably going to be to high to reliability report every positive to the FBI. The rate of actual CSAM is likely to be much lower than this. If it’s 1 in 10,000 uploads, you will have 100 false positives and 1 true positive.
That’s a possibility. I would be concerned that the false positive rate is so high compared to the rate of actual CSAM that the FBI would just block anyone using this for reporting as spam.
What might be done is to track the detection rate of users. If anyone is significantly higher than the average they might be uploading CSAM. Only issue I see with this is the detector doesn’t have an equal false positive rate across all content. It could be that the user just uploads pictures of their kids playing at the park a lot.