The text you quoted is purely about copyright/licensing, not about the maintainers' sanity.
The more relevant quote is: "In order to keep SQLite completely free and unencumbered by copyright, the project does not accept patches from random people on the internet. There is a process to get a patch accepted, but that process is involved and for smaller changes is not normally worth the effort." Though this is still about copyright, not about being swamped with PRs.
The issue of the maintainers sanity is the onslaught of random people or LLM's submitting packages, So how is not both quotes equally valid for the intended outcome of describing the restrictions required as to collaborate???