That's a key piece of the article. He 'trusts' Gemini to classify the posts, and never hand validates anything.

And he continues building on top of that shakey trust. Is this a good idea?

It just depends on what you're doing: sounds like he's just having fun with a hobby, so it's harmless.

All he's really done is work more efficiently to save token cost and time. But he hasn't validated anything, so there's no telling if he's wasting time or not. It's a hobby though....