I wonder if the DL who encroached saw the movement you described. Looks tome like he had his head down looking at the ball. If that’s the case, what about the clap caused him to jump? The movement causing B to encroach argument would be more credible if an upright LB had been the one who encroached
If you're comfortable allowing a QB to decide where, and when, to set the line as to what activity (harsh count, feinting or abrupt movement, etc.) may, or may not, draw the defense into a violation,
YOU can do that. Or,
YOU can decide where, when and how such behavior creates an "unfair advantage" and STOP it. Either choice is EXCLUSIVELY yours to make
(and live with).Many experienced officials will provide some additional leeway, the
first time they observe questionable behavior and (when their is
NO VIOLATION caused by it) to advise the QB(the behavior was observed and it should not be repeated, which
hopefully will avoid further attempts. If however, even that initial attempt draws the intended reaction, or ANY further similar efforts happen
YOU (and ONLY You) can decide how to address each.
Consistency is an important factor, but the PRIMARY LEVEL OF CONSISTENCY relates to the game you are currently working, and be
CLEARLY UNDERSTOOD by those participants.