The summary is meaningless, the language is critical, attend:
The Companies agree that because neither traditional AI nor GAI is a person, neither is a ‘writer’ or ‘professional writer’ as defined in Articles 1.B.1.a., 1.B.1.b., 1.C.1.a. and 1.C.1.b. of this MBA, and, therefore, written material produced by traditional AI or GAI shall not be considered literary material under this or any prior MBA.
It means gai material is not covered by this agreement unless a writer is asked to rewrite or adapt it as specified in later clauses.
Gai does not get writing credit, but there is no bar from having a gai written script other than the obvious fact that it would be effectively unwatchable without human editing.