if you look carefully, the 3 sentences are disconnected. they don’t form a line of reasoning.

if it had been starter, engine, and transmission, maybe you’d have a point, but instead it’s corroded battery, door handle, and tailpipe.

I looked at it carefully, and I’m not seeing what you’re seeing unfortunately. I interpreted the naive comment as a separate summary of their opinion, and then the rest of the paragraph was the supporting explanation. He didn’t dismiss the idea because it was naive, it’s the reason it is naive is why he was saying it wouldn’t work

Ah, the ad hominem, never a good sign for the proceeding argument.