That document may or may not stand the test of a court.It also may be valid in one jurisdiction and not another as in the case of both major airlines, they have divisions that are allocated rights under State's jurisdiction and as such State consumer laws apply. An Australian blanket ban may fail on that basis.
As I have said this could get very messy and I predict it will just disappear and be sorted behind the scenes.
At least now we seem to be arguing the actual rules etc for pax removing themselves from aircraft rather than the refugee/ bleeding hearts subject that in fact started the thread. This is not a political forum, Aviation matters apart and it should not become one.
Wunwing