I don't interpret Stoicism as succumbing to the naturalistic fallacy though (as in, what happens naturally is good, "is=ought"), but rather see it as an epistemological injunction, that is: you have to see things in the eyes and try hard to see and understand the world as it is.
A fair counterargument, and I would agree with you in an overall sense.
That being said, it is pretty clear from reading that a significant portion of the stoics did fall for that particular fallacy to one degree or another.
