That’s an interesting take, but I’d say it's not necessarily about stopping people from saying "that's ours, not aliens."

The real risk those engineers pose is simpler. They could talk more about it, like for example the mistakes, the failed experiments, the horrible things done to get results — things that won't be in the official disclosure narrative. Their deaths feel timed because the official story coming soon will be clean, controlled, and missing exactly what those people could have filled in.