First of all, that's crazy. The most charitable way I can read this is "we have inside knowledge that Apple will tighten security rules (again) and make it architecturally impossible to use VST2 on future versions of macOS" but that's a ridiculous stretch and they're most likely just posturing to scare people.
Speaking of inside knowledge, though, is it legally okay for you to post that? I hope it's not regarded as confidential communication.