When we read the story of Korach, our attention tends to be focused on the rebels. We don't give as much reflection as we might to the response of Moses. Was it right? Was it wrong?
It's a complex story. As Ramban explains, it is no accident that the Korach rebellion happened in the aftermath of the story of the spies. So long as the people expected to enter the Promised Land, they stood to lose more than gain by challenging Moses' leadership. He had successfully negotiated all obstacles in the past. He was their best hope. But as a result of the spies, that whole generation was condemned to die in the wilderness. Now they had nothing to lose. When people have nothing to lose, rebellions happen.