Comment by DavidSJ

I’m certainly not proposing that access to your SIM card should allow authorities to sync your messages! They should be stored encrypted on-device, and only exportable if you have login access to that device.

If authorities do acquire login access to the device, they can scroll through your chats and make screenshots, with or without an export feature. It’s true that exports make it slightly more convenient for them, but if you’re a serious target they’ll do it the hard way.

If Signal wants to provide some opt-in to disable exports, which can’t be retroactively reversed for old chats (otherwise it’s pointless), I have no problem with that. But if you’re worried about authorities with login access to your device, you shouldn’t be storing logs at all.