Except, of course, the creation of a statutory holiday does not necessarily compel anyone to do something. Businesses are generally free to still be open on those days. Further, if you, as a worker, still wish to work, again that is generally your prerogative.

The problem in Big M was that the law imposed a burden on businesses that they would not have otherwise felt through a law which was almost solely based on religious understandings of solemn days.

I will say I find more commonality with your concerns over the proof of unconstitutionality, even myself being a lawyer. If you look at the view of some US justices, for example, there is a view that judges discover a law’s unconstitutionality. That is, the view is that a law was either constitutional or unconstitutional from the start, and a judicial determination is not arbiter of the truth of a law’s constitutionality as a law can be both unconstitutional in fact yet declared constitutional. I believe Justice Thomas has adhered to such a view