I mean, sure, it could've been a crazy ex or a former business partner or whatever. But how many crazy ex's can one guy have? And he's pissed off god knows how many people by saying things? Strictly by the numbers this was almost certainly someone who hated him for what he said.
Statistically most people don't go out like Ozzy (i.e. spend a good chunk of your life doing something likely to be the death of you only to get dead by something completely unrelated)
I think it's unwise to be reflexively dismissive when norms that were previously taken for granted turn out to be ephemeral. I find a useful heuristic/gut check is to imagine explaining news from the previous week/month/year to someone who had just woken up from an extended coma.