There are very few situations where a dead man's switch would have helped these whistleblowers.
Once they have gone public and are at risk of being "suicided" they should have already released everything they knew. Sitting on it after already going public in any way only helps if the goal is to blackmail or extort the company, rather than to expose the company or protect others.
A lot of people have latched onto the idea of a dead man's switch (and I get it, technical solutions are fun to create), but the only part of the scenario it would help is before the whistleblower goes public, while they are still gathering information and haven't yet been discovered by the company. Even then, it wouldn't protect them from being killed, it would only ensure that the partial work is released in case they were discovered and prevented from finishing it.
You cannot be serious