Yeah, according to something reliable-looking that someone posted in the other thread, the real threshold determiner is Mach. Of course that's a function of temperature, which roughly translates to altitude and airspeed, as the first section quoted by CONSO says. So strictly speaking that's wrong too, but good enough for the purpose of whatever that document is. I was only clearing up the CONSO's perceived contradiction between that and the ATTitude referenced in the second passage.
I also agree that 1000 feet is likely meaningless, and was a result of 1) MCAS activates when the flaps go up, 2) the flaps go up at 1000 feet, and yada yada Chinese Whispers, 3) MCAS activates at 1000 feet. Oops! New wrong fact introduced into the collective consciousness.