Google Search for Discourse AI - Programmable Search Engine and Custom Search API

I’m setting this up and the current Programmable Search Engine UI seems to require at least one site to be configured.

If I try to delete the example domain (*.example.com/*) Google prevents it with “You must have at least one site to search.”

Because of this the “Search the entire web” toggle is disabled.

Is this expected behaviour now, or should the documentation be updated?