The post is unclear on this. I'm not sure where the "secret landing page" came into play here. They even show a screenshot with both options visible.

And they also say: "The visitors were given the choice to either buy the Made in USA or the Made in Asia version."

A/B would be randomly showing either ONLY the USA with higher price to some people and ONLY the cheaper Asian one to others.

However, even that isn't apples to apples as the price is obviously different.

I'm assuming they mean "in aggregate, visitors were shown both options" rather than "each visitor was shown both options".

They might mean it, but between the very clear language in the sentence and the screenshot they provided, I doubt it.

Seems more likely they don't understand A/B.

Ah, you're totally right. The screenshot has radio buttons for selecting one of the two shower heads.