I've always thought it was a dumb idea, this ban on "died suddenly," and looking back at the archives, I see that I said so in a short item four years ago. I could say more, but I don't think I need to.
SUDDEN SILLINESS (From the Boston Globe, Feb. 2, 2008):
I was talking with a former journalist about Stupid Newsroom Rules the other day, and he reminded me of one I hadn't heard in years: the ban on "he died suddenly."
In their 1999 book "The Trust," Susan Tifft and Alex Jones recount how Arthur O. Sulzberger, former publisher of The New York Times, learned from an editor at the Milwaukee Journal that suddenly was (supposedly) redundant: "'Everyone dies suddenly,' he said. 'One minute you're here, the next you're dead.' Years later ... Punch said the main lesson he took away was that 'in Milwaukee, you died unexpectedly."'
But this "rule" is totally bogus. Suddenly has always meant both "without preparation, all at once" and "unexpectedly," according to the OED. Trying to limit its sense to "instantaneously" is sheer crankiness.
Suddenly might have once been problematic, back when it was a journalistic euphemism. In the old days, "No one ever committed suicide," observes John McIntyre on his Baltimore Sun blog, but "people sometimes 'died suddenly."'
That usage, however, is no longer current, judging by the paid death notices in newspapers. Journalists may ration their references to dying "suddenly," but bereaved families use it routinely -- surely not as a euphemism for suicide.
Sometimes, it's true, the adverb is superfluous. In a report of death from an accidental overdose, a car crash, or a bomb, suddenly should go without saying.
Otherwise, it's perfectly appropriate to say someone "died suddenly." The adverb was never meant to imply scientific precision; it has always been about perception, not biology.