"I'm baffled by this comment. It's exceedingly rare for two middle-aged and otherwise healthy people to die without warning."

That statement is not even limited to whistleblowers.

If you restrict the population to known Boeing whistleblowers whose first name starts with J, the odds get even longer.

And if someone had predicted ahead of time that the second dead boeing whistleblower would have a first name starting with J that would have been quite astounding. But since we are waiting until after the two whistleblowers are dead and then choosing something we already know they have in common, no it is not any less probable.