I'd love to see a statistical analysis of whistleblower deaths on the US over the last 15 years. I'd be extremely susprised if it wasn't enormously anomalous.
It’d be hard to draw any conclusion. A whistleblower must be under extreme stress and pressure which in itself in some way or other will increase the risk of death — so that has to be taken account before saying the plausible cause for the excess deaths is assassination.
I was intending to release the information, so releasing it when I'm dead seems fine.
So why didn't I immediately publish it all while alive? Perhaps I preferred to control the flow of information, redact certain parts, or extort the organisation I was blowing the whistle on. None of those seem all that important to me compared to deterring people from assassinating me in the first place.