You can't ban voluntary speech, especially if your aim is to "sanitize" all speech on government property of any reference to theism (because that would create a bias towards atheism).
Southack - did the '43 decision actually say that part, against a bias toward atheism?
I hadn't noticed such, but it would be great news if they had.
No. The 1943 decision was before "under God" was even in the Pledge.