The fact that this guy didn't even say the name of his apps or what they do makes me pretty suspicious of the whole thing. There are enough developers who don't add any value but instead rely on spam, malware or piracy/copyright infringement to get big. I have zero sympathy in those cases, and support Google and Apple taking action against them.
The assumption that the engineer who was banned did something wrong is a bit misguided when there's no evidence for it, but there are countless examples of Google banning users who did nothing wrong. There are even some of those engineers in this thread posting their experiences of being banned by Google. The opaque and capricious nature of Google's ban hammer, and the special type of an ML-driven bureaucratic nightm…
You'll find a bunch of screenshots of random cheap looking apps that find wallpapers, phrases to tell to girls, spanish radios search.
So they most definitely rely on ads on their apps and not on building good ones.