Moshe Rabbeinu took an enormous chance when he implied to Korach that Hashem would back him up (with a miracle). What would have happened if Hashem had not provided Moshe with a miraculous intervention? Moshe was placing his position as shaliach Hashem, the agent of the Almighty, in jeopardy. Why did he do this? Horav Yaakov Kamenetzky, zl, explains that, with Korach’s rebellion, Moshe saw and was compelled to acknowledge that, sadly, there were Jews who still questioned Moshe’s Divine mandate to serve as Klal Yisrael’s leader. If this was the case, then all of the Torah that he had transmitted to them had little value. The first principle with regard to mesiras haTorah is that Moshe Rabbeinu was Hashem’s agent in giving the Torah, and its interpretation is based upon his teaching, since he learned Torah directly from Hashem. To impugn the integrity of his leadership is to undermine the Torah and its Divine Author.
Moshe was compelled to ask for a miracle, because the belief in the Torah was dependent upon this. He could not allow people to murmur and question the integrity of his leadership. A leader must “quiet” those who threaten his position. Low murmurs ultimately become loud voices, and, before long, one’s position is on shaky ground.