If you take the press release at face value, it means Android has fewer newly-discovered vulnerabilities on the open market right now. That's probably good news for Android, but there are alternative explanations too: maybe Google is paying more for their exploits to keep them hidden, for example. Or maybe Zerodium is trying to get Apple to sign a new/bigger contract and applying pressure.

This is all, indeed, a pretty shady business. I don't think there's anything authoritative we can say from the outside.