I think that was the point. They're trying to say that if, hypothetically, you knew the probability was 1/2, and you flipped it a million times and only got hea

I think that was the point. They're trying to say that if, hypothetically, you knew the probability was 1/2, and you flipped it a million times and only got heads, the probability doesn't change. The law of large numbers doesn't say this is impossible, just that it's incredibly, incredibly unlikely.