But in that case they would eventually be caught red-handed and won't get to do the "for the children" spiel and get it swept under the rug like it's about to be.
The government cares far more about other things than CSAM, like terrorism, human and drug trafficking, organized crime, and fraud. Unless the CSAM detection system is going to start detecting those other things and report them to authorities, as well, it won't deflect any concerns over encryption or VPNs.
Their private relay service appears orthogonal to CSAM… it won’t make criminals and child abusers easier or harder to catch, and it doesn’t affect how people use their iCloud Photos storage.
These people are commonly prosecuted using evidence that includes server logs that showing their static IP address.
Read evidence from past trials it is obvious. See also successful and failed attempts to subpoena this info from VPN services.
Only people with iCloud will be using the relay.
It is true on the surface the photos is disconnected from the use. However, Apple only needs a solid answer that handles the bad optics of what you can do with the Tor-like anonymity of iCloud Privacy Relay.
However, if you look more closely, the CSAM service and its implementation are crafted exactly around the introduction of the relay.