I wouldn't call it mismanagement. Many agencies thrive despite regularly delivering these types of experiences. It's a conscious choice they can easily rationalize because of the money.
This agency turned a one off $7k job into $46k by smooth talking and scope creeping an actual developer. I'm sure they're absolutely killing it doing the same to non-technical folks.
TinyPilot is clearly successful and growing. Any smart agency would nurture that relationship, deliver a great product, and secure an ongoing relationship.
By contrast, there's a huge amount of reputational risk in allowing things to spiral. They've walked away with more today but imagine for a moment the damage that would have been done were they named in this article. It doesn't take much for a brand to turn toxic and things to implode.
There’s a big legal risk involved in doing so and no upside that I can see.
I would hope he could get some satisfaction in knowing that he might be able to stop them from taking advantage of clients in the future.