Even if there would be some sort of inyan not to do this, I’ve heard stories of Rebbes who go completely over the top with this. Its like a Rebbe going ballistic because a boy started walking with his left foot instead of with his right foot.
IMHO making a big deal over something like this to a boy from someone who in their eyes represents Yiddishkeit, runs the risk of making the child think Yiddishkeit is all simply a list of their Rebbes whims