I absolutely am not an iPhone or iMessage fan, but criticizing a company for blocking someone who reverse engineered they platform to gain access isn't right in my opinion.
If a 3rd party app is allowed to utilise Apple's iMessage protocol/network, then every other messaging provider (WhatsApp, Telegram, etc) will be required to open up their platforms.
I cant wait to see the day where WhatsApp allows 3rd party apps to use their messaging network.