I think you’re misunderstanding them. They specifically mentioned SEO recipe sites, which are websites dedicated to being ranked highest on search engines, which typically means they don’t correlate with recipe quality, but with clickability (or whatever the algorithms like today). There’s a lot of them, so calling them spam isn’t necessarily wrong. Lots of people search for recipes, so it’s bound to attract it.
They just seem to be cautioning that the LLM might pull from bogus sources since there’s not really a straightforward benchmark for a good recipe that it might reference, and that you have to remember you’re using a tool. Your own intelligence is the real test. Which isn’t bad advice when dealing with AI output, but I think you already got that. I would say, don’t be baited into the idea that everyone is some hardcore AI hater because they are skeptical, there are certainly some, but assuming it alienates the many people that have surprisingly nuanced takes.
Google can still automatically mark your message as spam if enough people mark it as such or you trigger spam identification too often (this can happen if you send frequent test emails with not much in them) - it’s not neccesarily an attack on you. But plenty of spammers will send perfectly well verified emails today, so you are just caught in the crossfire.
Try sending a gmail account you still have access to a couple of genuine looking mails (eg. At least a paragraph of legible text and with a signature), then marking the messages as not spam. That worked for me. Even after that though, one line messages can still trigger the spam detection.