Interesting, they've softened their stance. Today, it reads

> In order to keep SQLite in the public domain and ensure that the code does not become contaminated with proprietary or licensed content, the project does not accept patches from people who have not submitted an affidavit dedicating their contribution into the public domain.

But it used to read

> In order to keep SQLite in the public domain and ensure that the code does not become contaminated with proprietary or licensed content, the project does not accept patches from unknown persons.

(I randomly picked a date and found https://web.archive.org/web/20200111071813/https://sqlite.or... )

Seems to be hardened not softened: a person who has submitted an affidavit dedicating code fo the public domain is at least minimally known, but a person may be known without submitting an affidavit, so the new form is strictly a stronger restriction than the old one.