This morning, after waking my fourth-generation Apple TV, I was prompted for a password, and was very surprised when I saw the password entry screen, because it was not the two-row layout I've grown to hate. Instead, I saw this:
Yes, that's the third-gen Apple TV's password entry screen, on my fourth-gen Apple TV. Just how did I get it to appear? Very easily, though it took me a bit to figure out exactly how I did it. Here's how:
And that's it. If you wake the Apple TV with the silver remote, and don't touch the Siri remote until after you get to a password entry screen, you'll get the grid. If the Apple TV pairs with the Siri remote, though, you'll get the new-style line entry screen.
I haven't extensively tested this, but I did try on two different fourth-gen Apple TVs, and got the same results on both. So if you want to use the old password entry grid on your new Apple TV, get yourself a silver remote (if you don't have one already).