This is the first time I've ever seen this message Disabled for Security Reasons. It appeared on our Apple TV last night. It was strange because all our other Apple devices were working fine. The thing said to go to "https://iforgot.apple.com" which is a pretty scary URL.
The last thing I wanted to do was to change a perfectly good password across *all* the devices that we have.
But apparently, I shouldn't have been worried, what happened was that it asked for the password and then it wanted a notification clicked on any of the devices that are already logged in and it was restored.
Apparently, this happens if someone types in the wrong password a lot. Pretty confusing to have it happen on an Apple TV. But if this happens to you, got to the URL above and reauthenticate.