I completely agree. If I buy a USB-to-serial cable in good faith, it's because I have a need for that functionality, not because I have any interest in what's inside the box or what IP disputes there might be between IC manufacturers over its contents.
The FTDI driver doesn't need to be compatible with chips which it identifies as possible counterfeits, but actively disabling access to them is a malicious act, and not acceptable.
This reminds me of the software that Sony shipped on music CDs some years ago, which tried to disable features on a user's CD drive in an attempt to prevent copying. That particular idiotic decision backfired, spectacularly, and quite rightly so.