I don't mean anything special by "state actor", I plainly mean: actions taken by a state.

Whether you consider those actions to be a threat would depend on an individual person's or organization's assessment of the impact of those actions.

Using your loose definition of "state actor" means that every single person who uses mainstream cloud solutions has "state actor" as a threat, whether they acknowledge it or not. It's not just the occasional person super focused on security as you're making it out to be - in fact people less in touch with security have a larger threat from their system being hijacked and used to distribute contraband bits, thereby running afoul of cloud scanning.

No it doesn't mean that, because threat assessments consist of multiple variables, including the footprint, probability, and impact of a potential threat.

That's a fancy way of saying "I've got nothing to hide".

No it's not. Consider the risk that a street criminal could throw a rock through my window and steal my computer off of my desk. Do I put bars on my window? No. Why? Because I have nothing to hide? No, because I don't consider that attack vector to be a high enough priority that I need to take steps to mitigate it.

Threat assessments are purely an engineering exercise. This is orthogonal to the ethical, philosophical, and political discussion of civil liberties. If you have ethical, philosophical, or political concerns about this topic, those are something to be addressed in their respective realms. It is naïve to believe that engineers have power to protect anyone from abuses of civil liberties. Apple hardware engineering team is neither capable nor equipped to be addressing these concerns in their designs.