I actually agree that the US Constitution is "overrated" (at least by some who seem to put it on a pedestal), so to speak—mainly because the Second Amendment is a malignant anachronism at this point.
However, in a diverse and pluralistic society, I simply see no way for a constitution not to be secular if the state is to remain fair and equitable for all citizens and residents. What one person may regard as a religious truth may not be perceived as such by another, and vice versa. I'm pretty sure many of the same people who support state favoritism toward their religion wouldn't like it if another religion were favored over theirs by the state.
Theocracies are almost universally undesirable places to live for most religious minorities. Having lived in one myself for about two decades, I'm firmly of the opinion that officials like this governor are irresponsible fanatics who are either indifferent to others' rights or oblivious to just how damaging theocratically minded laws tend to be.