By himself? No. I don't think the precise authorship even matters. It is represented as coming from Zuckerberg, as an official company statement: "Mark Zuckerberg just shared the following with Meta employees". Zuck publicly endorsed it as his views on the matter, regardless of the pedantic details of who exactly wrote which sentences. I don't think it makes much sense to distinguish the author(s) from Mark.
When the President of the United States gives a speech, you don't analyze the speech as if it were the views of the speechwriter(s). Of course the POTUS is just reading from a teleprompter, but the writers are hired by the POTUS to write for him, as is the case with Zuckerberg too.
"The author" is a bit of a strange way to refer to Mark Zuckerberg himself.