I never saw Plato as a Straight-Out Scientist----more of a Metaphysical Philosopher. Certainly He Is not in the Mold of the Pre-Socratics, who were more Natural Scientists/Philosophers who were Concerned with the Universe and Its Meaning and Workings.
It was Socrates who Flipped the Whole thing around and Declared that Philosophy would henceforth Concern itself with Man almost Exclusively.
Plato merely contimued in the Mold of His Master and added Political, Metaphysical Concerns to the Study Of Man.
Aristotle was More of a True scientist because he concerned Himself with the Physical Workings Of Things and How They related To man in a Scientific, Political, Ethical way.
Although I DO agree with you that Plato is the Greatest Philosopher Ever…
Not so much a Scientist, though.