Ben Levi,
You are missing the point here!
1.) Rabbi Slifkin’s main point is simply that when Chazal say a scientific statement you don’t have to accept it. (So for example if Chazal say the world is not billions of years old, or that all animals that ever lived were created in one day a few thousand years ago, or that the Sun circles the earth etc etc etc) you don’t have to accept that as fact. Rabbi Miller and the Yeshivish establishment had for quite some time said that when modern Science contradicts Chazal’s statements then the Modern Scinetists are wrong.
2.) It doesn’t make a difference if only one person said that Chazal got their Science wrong and everyone who came after that one person argued very forcefully on him. If physical proofs have made it clear that Chazal’s scientific statements are not literally true, then they weren’t and whoever said they weren’t was correct. It doesn’t matter who argued or how forcefully they did so. Facts are facts no matter who on them.
(I am not discussing the proofs themselves here or if modern scientists have proven their assertions. This is not the correct venue for that discussion. Just pointing out that you are missing the point here)