The problem with that line of argument is that it tries to counter one false or misleading stance with just a different false or misleading stance, which leaves the response vulnerable to debunking.
YES e2ee absolutely lets people doing bad things hide in the dark, and there's no sense denying that. Those technologies protect the privacy and hide communication of all without regard to their guilt. Any denial of that will come across as obviously wrong.
Instead the argument should be that protections of privacy for all, for YOU, are worth supporting as we find the balance between personal rights and law enforcement priorities.
Yes, if we had a camera in every bedroom we'd catch more people doing bad things, and not mandating such cameras does hamper law enforcement, but we're willing to accept that trade off. We don't deny that police cameras in bedrooms would catch more; we point out that we're willing to make that trade.
Same here.