NFHS Defensive movement prior to the snap

Question
This is regarding NFHS varsity level football.

Recently there have been actions by a defense that can be interpreted to be an illegal shift - which can be considered a violation of 7-1 art. 7b.  Their defensive line will get set and (shift) slide over to their new alignment.  With this there is no question.  However, several times during a game, their entire defensive line will jump out of their stance simultaneously, throw their hands out like their coming at you, then shift over and rest.  

This action has been matched to 7-1-7b but all references I could find are on the offense.

My research shows this to be closer to 9-5-1d ... "Use of disconcerting acts or words prior to the snap to interfere with (opposing player's) signals or movements." which would be a 15-yard unsportsmanship penalty.

My understanding is that "No player shall use words or signals that disconcert opponents when they are preparing to put the ball in play. No player may call defensive signals that simulate the sound or cadence of (or otherwise interfere with) offensive starting signals."  

The problem is that this does not adequately address the defensive line quickly coming out of their stance as noted above.

I would appreciate your comment on this situation.

Thank you.

Answer
Elmer,
Outstanding question and your research is right on.  Rule 7-1-7b only applies to the offensive team, not the defense and the only rule that comes close under the high school rule govern such conduct is the unsportsmanlike conduct rule of 9-5 and Use of disconcerting acts or words prior to the snap to interfere with opposing team's signals or movements.  However the high school rule has permitted quick shifts and movements by the defense which may draw the offense to false start.  

Thus the actions by a defense you inquire about is unfortunately legal and permitted.  Under NCAA rules it would not be permitted.  You are correct that the current NFHS football rules does not adequately address the defensive line quick movements that can be used to draw the offense offside.  There is an old mind set that the offense knows the snap count and any action by the defense is not  creating a disadvantage.