I didn't compromise the security of iMessage as a whole, it just exploited a way to get people into the system that was not planned.
Imagine there is a theme park that has normal ticket booths and some requirements there to get in. Then there comes a Beeper that finds a hole in the fence on the perimeter and sets up their ticket booths there. It's in theme park's best interest to close that hole and cut off the revenue stream of somebody pigging back on their theme park.
Except they charge a thousand dollars to enter and then let everyone else in for free but they have to wear a badge and the pictures they get from the roller coaster photo booth are 240p.
And no one is obligated to come to the Theme park. There's an entire world of people who never visit the theme park, mock the people who do, and couldn't care less about it. But some people want to be included as going to the park, when they don't. Some people are very judgy and don't want to talk to people who don't go to the park...
Imagine there is a theme park that has normal ticket booths and some requirements there to get in. Then there comes a Beeper that finds a hole in the fence on the perimeter and sets up their ticket booths there. It's in theme park's best interest to close that hole and cut off the revenue stream of somebody pigging back on their theme park.