2 points
The limitation was added after the fact anyway, like I mentioned in my edit, secure enclave wasn’t added until the A7 chip, which was first used in the iPhone 5S in 2013, two years after iMessage became available.
3 points
Although true, it was added to make iMessage (and every other service) more secure, not just as some sneaky way to keep iMessages off android devices.
1 point