After reading the article, I think the turning point was when Terms of Service were unilaterally changed to forbid selling his service to new customers. If he'd been permitted to keep selling to new customers, he'd have been able to continue.
Would a good analogy would be Apple banning other web browsers on iPhone, because they are an important part of the iPhone experience?
His conclusion was that this was a limited time opportunity, which he profited from and it has come to an end.
Apple bans other browser engines because can they run arbitrary code, which is not allowed per the store rules. They are fine with other browsers on top of WebKit.
