I don't think there's any truth in what this breeder told you.
As you know, I've had a lot of broody hens.

I usually take them off their nest at dusk, but sometimes I do it in the day.
What happens here, day style or night style (off nest and onto roost bar and shut in for night),
is they do go back to the nest and will sit on an empty nest for a while. But, so far, all have given up as long as there are no eggs in the nest. A couple have sat after eviction and waited until they, or another hen lays an egg in the nest. In this case, they stay broody and sit.
To be sure of discouraging a broody hen from sitting, I've found removing the eggs and destroying the nest (strip out nest box) works for 95% and for the other 5% confinement in my house for two or three days.