> Then I can’t help but think: if the author of the article didn’t even understand this, how can the rest of the article be correct if it started from a biased and almost false premise?

That seems pretty unfair. The article is clearly structured to treat the Galileo thing as an example, not a premise. It is supposed to be a familiar case to consider before going into unfamiliar ones. In that sense it clearly still works as an example even if it's false: does it not set you up to think about the general problem, even if it's a fictional anecdote? It's no different than using some observation about Lord of the Rings or Harry Potter as an example before setting into a point. The fact that it's fictional doesn't affect its illustrative merits.