Does your son want to go to the funeral?
Our kids have been to several funerals (mostly of elderly family friends since their grandparents are all still alive). I feel that it shows them that death is a normal part of life. The ritual can provide closure.
That said, we had a tragic, expected death in the extended family last year. The school counselor advised us to let the kids attend the funeral if they wanted to go. My DD9 wanted to go but DD7 did not. DD9 wanted to be with the family. DD7 said that she didn't think that she could handle everyone (grandparents, aunts, uncles, and cousins) being so sad. She is highly empathetic and it would have been very difficult for her to watch others in pain. I think that each girl made the right decision.