If you are referring to Mass Manufacture, the unique provides Wat additional abilities. The abilities provide the tech to other characters. Ability effects persist after death. Overseer on the other hand provides a benefit directly through the unique and that benefit should be lost if Wat dies (which I’m 99% sure it does). It is consistent in this case.
If JKA does his AOE, gives everyone offense up, and then dies, the offense up doesn’t disappear from his allies. In the same way Wat’s tech doesn’t disappear as it’s a locked buff provided by an ability.