This is an interesting topic to me. I work in mental health with Medicaid recipients. I've seen numerous individuals and families affected by suicide. All of my clients are close to the federal poverty level.
With any trauma like this (a significant loss, in this case) there is nothing that takes away the pain. There will be times in each relative or loved-ones lives where they are unable to shake the feelings of guilt or anger or loss that a suicide leaves--it won't help them to think "hey, I have a million dollars so it is okay..."
That said, having a lot of money does offer opportunities to those affected people to open doors to do things in life that are fulfilling, meaningful and which could ultimately re-instill a sense of purpose if it was lost by the loss of a loved one.
My clients who are struggling in all areas of life have more to worry about and the associated depression from the loss becomes a chronic life-state, often wrapped up with numerous other losses (divorce, homelessness, etc..,), getting to the point where the losses has been so numerous that you can't locate the reason for depression or PTSD back to any particular 'event'.
I guess to summarize, I would say two things:
1) The money could mitigate some of the potentially negative results on his family members because it is an additional resiliency factor. All things being equal, I would hope someone affected by a parental suicide would have money, rather than living in poverty. If his kids find that nothing in life makes them happier than golfing, or model trains, or traveling, or cooking good food, then they will be better able to access those activities because they have money. It's pretty simple.
however...
2) Depression is contextual and happiness acts as a drug. Happiness is the result of neurotransmitters acting on our brains. A lack of, say, Serotoin, will make you literally feel depressed whether you are wealthy and famous or down and out. Status doesn't matter. People who think he should have been happy because of his status are missing the neurological mechanisms behind depression.