You aren't turning off encryption. You are just causing the HDCP engine not to be able to read the keys because you'd corrupted the internal memory address of the keys with that bit so when a source tries to authenticate, it will fail as if the source was authenticating with a non-HDCP device.
Of course, when the memory address is correct and the keys are read, it'll authenticate and the source will encrypt.
You are not turning off encryption, only the source can do that. You are just giving the engine the wrong key address-- it's just a hack that causes encryption to fail-- it doesn't tell the source not to encrypt.
What a source chooses to do with an authentication fail is up to the source. Some will stop encryption but most will just not transmit anything but snow or black screens.
Dave