Funny, I heard the same thing a while back from a couple of sources. Never gave it any thought.
As the great, late Tone mentioned in an earlier post, I too did hear, that if the ABS is at full light ON, the module is "most likely" not to blame, but possibly a speed sensor.
When FLASHING, the ABS module is failed as the circuit tripped and did not return from the module, meaning module failure.
Just what I heard.... I won't be held liable. .