Clearly we need those dates only on our calendars. We can dump all the religious nonsense as they are all not official holidays. That would be a good result as far as I am concerned.
Except that you forgot about this part:
Ex. Ord. No. 11582, Feb. 11, 1971, 36 F.R. 2957, provided:
By virtue of the authority vested in me as President of the United States, it is hereby ordered as follows:
Section 1. Except as provided in section 7, this order shall apply to all executive departments, independent agencies, and Government corporations, including their field services.
Which appears to limit it to Government Employees.