I was going to say this is BS, and that Gaileo's big achievement was not undermined by this argument. I then found that what I was going to argue was his big achievement was not as original as I had thought: https://en.wikipedia.org/wiki/Galileo's_Leaning_Tower_of_Pis... On the other hand he still seems to have made a significant contribution to laws of motion in his writing, but I am not sure.
It still took like a thousand years for this to be experimentally demonstrated.
The important part of this "thought experiment" in the history of science is that it is part of the shift to empiricism that really drove science. It was important to go from "Well they were smart and they said, so it must be true" to "I don't care how smart you are, what you say doesn't match the data"
This is important, because "smart" people like Archimedes said a lot of stuff that was never true, but was taken as true for a millennia, often because it "sounded" right or obvious. More importantly, Archimedes could have done the exact same experiments that Galileo (and others) used to demonstrate he was not correct. There was no technological advancement required. He didn't, because the philosophy at the time was to "just think really hard about it" and "reason from first principles" and you would obviously get the right answer if only you are smart enough. Who needs data? You're smart and you thought hard about it, so you cannot be wrong!
People should recognize how important that is to remember in the current world.