Have you ever driven a Tesla and rebooted it while driving? Have you ever even driven a Tesla at all? Or is this just a guess based on your experience with custom ICE cars?
In the rebooting state it's probably still safer than any other car. You aren't missing any critical information that you can't see by looking out the window (the approximate speed). There is no gear shifting, no fuel, and you would have been warned well before this if your charge was low enough to cause alarm. I can really think of nothing you need on the screen that you would seriously miss as a matter of safety while it's rebooting for a few seconds, as long as you're being attentive as a driver, which you should be.
In the rebooting state it's probably still safer than any other car. You aren't missing any critical information that you can't see by looking out the window (the approximate speed). There is no gear shifting, no fuel, and you would have been warned well before this if your charge was low enough to cause alarm. I can really think of nothing you need on the screen that you would seriously miss as a matter of safety while it's rebooting for a few seconds, as long as you're being attentive as a driver, which you should be.