I highly doubt his death was CAUSED by AAS use. I think he was intelligent enough to not always run orals like some people seem to think. I'm sure it influenced it and played a part, but AAS absolutely didn't kill him.
However, I would be very surprised if it didn't have to do with him walking around at his weight, and his required diet to get to such a size. These men eat INSANE quantities of food, and they're not always "clean" foods either. Mike Matarazzo talked about eating something like 8-12 pounds of red meat per day or something like that -- and you KNOW that is common with pros to reach the size they are.
I completely believe its the dietary practices they take on to get to their size. Then, once they reach their size they just can't ever seem to let go of going back to a normal size. So they continue to eat INSANE amounts of food even though it does nothing for them but make them feel better about themselves. It has been proven many times over that being so far overweight is detrimental for your health, be it fat or muscle. Put all this together with what steroids do to the body when you're using insane doses for long periods of time (Nasser was obviously still using gear at his size).
I wish these pros/former pros would really take care of themselves and stop trying to hold onto their glory days once they retire. It'd definitely help them survive longer.
I also have no doubt many pros have suffered major health issues from substances such as Lasix (diuretics, etc). And MANY of them also abuse(d) narcotics which can cause damage. Everything added up over time = early death unfortunately.
I really like Nasser, he was a very close friend to one of my best friends. So when he died it impacted a lot of people around me.