> only 48 testers/flippers

I assumed they did these coin flips were done using a machine. But I guess they wanted to test if human flippers because they wanted to make claims about the human coin flip phenomenon.

If you programmed a machine to flip a coin in the same exact way every time, would you not expect the coin to land the same way every single time? If you program some randomness into the machine to simulate human flipping, then you'd simply move scrutiny from the coin to the machine's programming.

I think the result could be better described as "humans tend to flip fair coins to land on the side they started".

But if you get someone to flip a coin thousands of times for a boring reason, I would lose confidence that they are flipping in the same way a normal human would.