I think people should have the right to encrypted, secure private messages, but that doesn't mean platforms get carte blanche to do whatever they want in how they design these services or how people behave once they're on them.
I'll give you an example. You want to exclude things that say you must take down individual pieces of content from encrypted messaging, because that requires breaking encryption. But if you say, “You need to articulate what you believe the risks are of how your product is designed today and have a plan to address them”, that leads to things like what Instagram did maybe two months ago. They said, “We're going to make all under-16 accounts private, because we found that adults were contacting these children.”
That's an example of a behaviour and design intervention, not a content intervention, involving private messaging.