I don't know whether that's true or not, but either way it doesn't matter.

The AoA sensor does not function on the ground, it's basically a windvane and with no air moving over it, it would move to whatever angle gravity dictates.

It should detectably not function, though, right? On level ground, with zero airspeed, it should always be in a certain position, and a deviation from that should be something the plane can detect and compensate for.

There could be a sufficient amount of friction in the system such that it could be in any position when the air speed is zero?

Unless it's windy.

There are two complicating issues:

A certain air speed is required (to turn the weather vane, as it were).

While in ground effect, the air flow is different from the airflow in flight (away from the ground), so apparently a certain altitude above ground is required for the indication to be considered reliable.

However, I believe that it should be possible to recognise a sufficiently defective AoA sensor during the take off roll, and possibly in time to abort the take off. However, not sure whether pilots are briefed to do so, as that is a risky manoeuvre in itself, and a missing AoA sensor should not be any problem per se (in the absence of MCAS that is trying to kill you).

A lot of aircraft systems key off of "weight on wheels" and other flags so they can ignore certain edge cases.