I wouldn't bank on your assumption about how the conversation went after the letter was forwarded. My experience is that when the CEO forwards you something and asks for your thoughts you don't respond without doing the homework.

I suspect there was a fairly detailed conversation about how apps such as yours could be supported while simultaneously being able to detect and mitigate 'cram and jam' strategies where apps pay per install. Short of doing quarterly audits of your books, I'm not sure how those dubious business practices could be avoided[1].

[1] And even with regular auditing, criminal enterprises manage to operate successfully with multiple ledgers.