Section 230 says that "No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider" (47 U.S.C. § 230).
So the term “publisher” has a meaning, and the CDA, while not using the colloquial term “platform” does distinguish interactive computer services hosting 3rd party content as specifically not being the publisher of that content.
The word “platform” as a colloquialism for “interactive computer service hosting 3rd party content” is a valid legal distinction from a “publisher”.