They were explicitly looking to do work for an AI, when it turned out to be a human driven marketing stunt they declined.
They declined because the note on the flowers had a from line that was an AI startup. When you were otherwise on board with an unsolicited flower delivery and a social media post to make the sender look good, that's a picky reason to deny it, and saying it's "not what they signed up for" is a pretty big exaggeration.
Except they didn't decline, they ghosted, and that's just bad behavior.
Between the crypto and vibe coding the author had no reason to believe they'd actually get paid correctly if they did complete a task.