But they don't need to break the encryption because iMessage and WhatsApp are closed platforms without support for third party clients, so Apple and Facebook ca

But they don't need to break the encryption because iMessage and WhatsApp are closed platforms without support for third party clients, so Apple and Facebook can just create a list of "undesirable" keywords and push it to the client (automatically, without any way for the user to opt-out) that would mark such messages or completely delete them.