Then the rants you boasted and the like in your previous statements within this thread have become irrelevant. If the BD has the thought process that because of injuries and other situations that utilizing traditional grip is damaging the kids more than if you were to utilize a matched grip, then it is in his eyes that in the best interests of the students, matched grip is the way to go for the drumline as a whole. Thus, as you are a person working under and alongside said director you may wish to take that and adjust your teachings as needed.

Now if you were to offer lessons and tips on playing while utilizing traditional grip on the side so the students that wish to march DCI and continue into other facets of percussion have that extra knowledge, then by all means go for it as it helps expand the repertoire of the musician for said facets (Old Fife and Drum Corps, jazz ease of getting around the drums, so on and so forth)

Edit: I see I made my post about a month too late. Still, that should be in the back of any instructor's head.