There is a custom for chasanim to say a drashah, and then people sing in and stop him in the middle. Rebbe Aharon, the Belzer Rav zt'l explained that by singing in, and not letting the chasan finish, we are teaching the chasan that he doesn't always have to have the last word. If some oppose him and want things to be done differently, he can allow that to happen. With this attitude, there will be peace in his home.
Opposing Moshe was Korach, along with two hundred and fifty heads of the Sanhedrin. The sefarim say that they had logic and explanations for their machlokes. Now, how can an average person know which side to go to? Moshe is on one side, but there are great people, with proofs and logic, standing on the other side. How can a simple, unlearned person know who is correct and which side he should join? Some answer that when they see that Dasan and Aviram are on one side, that is enough indication that this isn't the side of kedushah, and he is better off standing on the other side.
