This statement from Wyden's press release seems to be in contrast to Chris Cox's reasoning in his journal article [1] (linked in the amicus).
It is now firmly established in the case law that Section 230 cannot act as a shield whenever a website is in any way complicit in the creation or development of illegal content.
...
In FTC v. Accusearch,[69] the Tenth Circuit Court of Appeals held that a website’s mere posting of content that it had no role whatsoever in creating — telephone records of private individuals — constituted “development” of that information, and so deprived it of Section 230 immunity. Even though the content was wholly created by others, the website knowingly transformed what had previously been private information into a publicly available commodity. Such complicity in illegality is what defines “development” of content, as distinguished from its creation.
He goes on to list multiple similar cases and how they fit the original intent of the law. Then further clarifies that it's not just about illegal content, but all legal obligations:
In writing Section 230, Rep. Wyden and I, and ultimately the entire Congress, decided that these legal rules should continue to apply on the internet just as in the offline world. Every business, whether operating through its online facility or through a brick-and-mortar facility, would continue to be responsible for all of its own legal obligations.
Though, ultimately the original reasoning matters little in this case, as the courts are the ones to interpret the law. In fact Section 230 is one part of the larger Communications Decency Act that was mostly struck down by the Supreme Court.
EDIT: Added quote about additional legal obligations.
[1]: https://jolt.richmond.edu/2020/08/27/the-origins-and-origina...