How much of this is a long-term bet that the US DOJ's antitrust case against Apple (at least the iMessage-specific argument) will result in the forced opening up of the platform, such that Beeper (now Automattic) will sustainably function?
But let's say it's not antitrust, which is what your question is trying to imply. Apple will still need to answer to the other ways it makes third-party messaging apps worse on iOS - automatic offloading and share extensions being two examples.