Thank you, everyone, for all of your answers! I will contact both the cemetery and funeral home, hopefully they might have some further insight. I'll update this question and post another comment whenever they reply.
Also, to Harry, yes. A person being buried a day or two days after their death seemed to be pretty common in Huntsville and the surrounding areas, especially among more lower class families.
If I don't squint and push my head up close to my computer screen, I can see the possibility of "He was subject to epileptic convulsion." But, like Melanie, I'm on the fence about it too. For now, I'll just leave the cause of death up to interpretation when I write his bio and include everyone's brainstorming in the research notes section.
Thanks again everyone! This means a lot to me.