Ars is a terrible source of news, this isn't their first offence.
Seems like an obvious thing to do whenever writing a "notable person X has died" article.
The obituary, for instance, says he died on the 27th. The Macomb County records office [0] says he died on 26 September 2016.
[0] https://macombvitals.macombcountymi.gov/death.php (search for David Hahn)
Not saying it was suicide, mind you, I have no information aside from what we all have.
His internet public memories page was full of relatively close friends and relatives in shock. So your situation or an accident. The police would be involved either way. I pulled the police log for the week of his death of all police calls in that city and found nothing logged along the lines of any bodies being found or violent crime or whatever. As near as I can tell the only interesting thing that happened in the town where he died on the day he died was a very major traffic accident, the worst thing to happen in town in weeks before and after. There was a twitter-worthy hours long road closing due to a major (aka fatal) car accident. Absence of finding anything proves nothing, perhaps they intentionally censor suicide calls or it has to be considered that "suicide by car" is not unknown, but I would not be surprised if he died in that specific car accident.
Separately, the funeral home "tribute wall" has comments which would seem to imply suicide or drug overdose. In particular, it would seem very odd to say "I believe David finally has the peace he so desperately needed" unless his mental state played a role in his death: http://www.wasikfuneralhome.com/obituaries/David-Hahn-2/#!/T...
http://www.dailymail.co.uk/news/article-2506549/Uh-oh-Radioa...
He also admits to being schizophrenic and talks about how hard his mother's suicide was on him. It sounds like this guy had a hard life. I'm guessing he followed her lead.
RIP David.
In this case with a one person test group.
Well, if he was e.g. struck by lightning just before he died, then the odds that cause of death is related to exposure to radiation years ago go way down. The article sadly doesn't even give anything to go on, or even mention the omission of anything about cause of death.