This was indeed one mitigation used by a site to prevent bots hosted on AWS from uploading CSAM and generating bogus reports to the site's hosting provider.[1]

In any case, I agree with the sarcasm. Blocking data center IPs may not help the OP, because some of the bots are resorting to residential IP addresses.

[1] https://news.ycombinator.com/item?id=26865236