Ok, that's fair. But what should Apple do in response? If they did not break it the first time, Beeper would be making $2-3/month off of their services.
It would have also shown that Apple's platform isn't as secure as they position themselves to be if someone other than them can utilize their services without their permission.
There was no winning move here for Apple except to close access off to secure their closed protocol. It was just inevitable at that point.
Is it really a security problem though? Something can be secure and support 3rd party clients. More likely this is just a walled garden problem. Because if it was just a security problem then Apple would have released a 1st party iMessage app for Android before now.
This doesn't answer your question though. I guess what I'd have liked to have seen is Apple release a public iMessage API. I know that would never happen, but one can dream. The approach Apple took was certainly predictable. I have no sympathy for Beeper either.
It would have also shown that Apple's platform isn't as secure as they position themselves to be if someone other than them can utilize their services without their permission.
There was no winning move here for Apple except to close access off to secure their closed protocol. It was just inevitable at that point.