Was the founder just using the company as a front to collect dubiously legal artifacts perhaps? Basically as a way to insulate himself behind his company in case some irate government came looking for them.

That’s not quite the correct framing. The RFRA allows a “person” to sue the government where a law impinges on the person’s “exercise of religion.” Hobby Lobby involved two separate issues. One, does “person” for purposes of the RFRA include a corporation? The Court answered yes, that’s the usual meaning absent contrary intent. Two, is a privately held for profit corporation a “person” capable of "exercising religion?" DHHS conceded that non-profit corporations were capable of exercising religion. (The dissent did not dispute that either.) So the Court's decision was a straight-forward application of that concession, based on finding no reason why a for-profit corporation should be treated differently.[1]

The underlying principle therefore wasn’t “blurry." Corporations have separate assets from their owners. But they are controlled and operated by people for various purposes. The government cannot use the fact that the inanimate entity lacks rights in order to indirectly impinge on the rights of the people who legally own and operate the corporation. That basic principle wasn't disputed by either DHHS or the dissent. The only issue was whether for-profit corporations should somehow be treated differently than non-profits.

And that general principle is clearly correct. Thought experiment: can Donald Trump issue an executive order requiring Google to post in its front page a banner encouraging people to vote for him? If not, why not? Whose rights are violated?

[1] I actually disagree with the DHHS's concession. Corporations can't "exercise religion." For this particular case the distinction ends up being academic, because that just means that the owners are the ones who should have brought the RFRA suit, not the corporation. The owners of Hobby Lobby definitely can exercise religion, and regulating a corporation they have the right to control can be an infringement of that right. As Kennedy noted in concurrence, the holding of the case is narrow.

Mostly Christian, yes. There are some Jewish relics, and a few other items. Much of the collection is very old/rare, seriously museum-level content & quantity.

Content includes: Gutenberg Bible, first-printing King James Bible, Dead Sea Scrolls, metal-imprinted Torah, famous misprints ("thou shalt commit adultery"), jewel-encrusted Bible given by Yassar Arafat, bible illustrated by Salvador Dali, and lots of ancillary relics I don't recall at the moment. If you get a chance to view the traveling museum, do so (regardless of your inclinations).

I just wanna try using Reason.