Moses was upset that all three goats were not burned in the sin offerings. He investigated throughly and decided that the culprits with Aaron's sons. Aaron listens, but then tells Moses that it was not the sons, but it was he who made that decision. Moses says he understands.
What I like about this parshah is that Moses listens and changes his mind. Unlike a king, Moses is able to change a view that was well-researched with a “double” investigation. Normally a mourner can't do a sacrifice, but Aaron says he is a high priest so he can do it. Is the message that the rules aren't the same for everyone and every time?
It is interesting that priests can't go to funerals unless they are a brother, wife, unmarried sister, child, or parent. I wonder what the reason for that. Is it that they'd be too busy to take care of the living?