To me it's the opposite: I expect to be able to read the note which is on screen
indefinitely, that is: exactly how I leave a notebook open on a page.
Physical security is a non-issue in this class of device IMHO. It's the same security I expect on a physical notebook. If that gets stolen, it's stolen. If we can get something better (like full encryption with pin unlock - so that the other non visible pages are safe) than I would be more happy, but the current status is still perfectly fine.
What's NOT ok is the reliance on the cloud features. There's no encryption. No control on sharing. It's either all or nothing. You can turn this off, but then you cannot send the notes elsewhere (it's fine if I'm intentionally sending one page to somebody I know he can receive it). Screenshare also stops working, despite being a dumb vnc connection wrapped in ssl, just because the central randevouz point becomes inaccessible.
This is also why this makes this device unfit for company use IMHO: your users cannot be compliant with any sort of security policy unless they disable everything and just use it as a dumb notebook. Getting it stolen is a non issue: you can get a notebook stolen, it's your fault. But if I cannot control the cloud features in a fine-grained mode, then it's outside of your control and that's what makes the device really unfit for corporate use.
I hope remarkable is listening. I opened several tickets for this: just allow me to disable sync for a folder or everything (without killing send by email) would already be a start.
It's otherwise an amazing device, but a device you cannot trust with the cloud features, which is a major shame.