Canning Parler is Apple choosing not to advertise and send you an app they don't like, i.e. it's Apple exercising it's own right to free speech. Agree or disagree with it, it's categorically different from Apple spying on what the files you have are saying (not even to or via Apple) and reporting it to the government.

Apple also disallows you from installing things without going through them, so “choosing not to advertise and send” has a lot more significance than your wording implies.

It’s not like they have a curated App Store for apps they like; there’s literally no other way to add software to the device.

Right, but the fallout that prevents you from installing it is an incidental consequence of Apple choosing not to promote it and Apple choosing to use it's monopoly on app distribution as an income channel.

Speech not happening because Apple didn't go out of it's way for it to create a route for it to happen without Apple being involved, isn't really that shocking or similar to Apple scanning private files. (Apple being allowed to prevent you from installing what you want on your phone is shocking from an anti-trust perspective, but not from a speech perspective).