First and foremost, they want to keep his reputation intact for the ages. There may have been medical conditions that they did not want made public.
Mri last week and a dropped cell phone convo to announce the death:
FYI justice of peace stated it was not myocardial infarction. I don’t believe they said it wasn’t “heart attack”...many ways for the heart to skip.
Like murder?
If his family is adamant they don’t want an autopsy, they have reasons that are private. Lots of possibilities.