Earlier quoted context omitted.
His first sentence about privacy and security is nonsense, but his second sentence hits the nail on the head. If the richest company in the world wanted their chat app to run on Android, it would by now. It's strange Apple doesn't sell an iMessage Android app, but I'm sure they've had somebody do the math and found out that it's more money for Apple in the long run if they don't.
Completely agreed about the nonsensical first claim. We have many third-party clients for other messaging platforms where privacy and security are a primary feature. It's completely tenable, especially for a player like Apple. Or put another way: If the privacy and security of imessage is compromised by someone building another client, I'd argue that you never had either to begin with.
That's like saying the internet protocol is neither private and secure because people willingly use random public Wi-Fi