So take using a sledgehammer to crack a nut.
What they should be doing, is rather then increase the risk of for the majority who use encryption for valid reasons (privacy, not nefarious), is invest in services to allow individuals to gain help, in a manner where they won't be ostracised and at risk, all from trying to come forward and get help to amend their behavior.
I am father myself, and like a majority (being a parent is a moot point really) am appalled and disgusted by CP, but me being that way won't stop individuals from succumbing to obtaining CP. Some of them do this even though they know it could trash their seemingly normal life (they often have their own families who are totally unaware). This to me suggests there is some sort of psychological disorder at play, and these people need professional help and intervention.
Trying to snoop on everyone, to seek these people out won't achieve anything. They are willing to offend even with extreme risks already in place (being labelled as a pedophile for the rest of your life). Them being snooped on won't stop it all, the same vicious cycle will continue to play out, but now with all of us lacking a basic right to privacy.