It reminds of a concept, which barring a better name, is "action through inaction" — if you know an employee is unhappy through external signals like these, you could make the active effort to not engage with them knowing that it may lead them to quit; instead of a lengthy severance/redundancy discussion.

I've seen similar insights, derived from a person's social-graph through email exchanges, and it was decided to not be used by managers as it could be a liability.