No, it only works for family members as it was designed to be used for traits.

The work around is to use a CharacterTurnStart or SettlementTurnStart event with a I_SettlementOwner conditional for that settlement. Easy to start, but it's hard to stop it triggering on subsequent turns (terminate_monitor will not stop it triggering when you reload the game) - you can block it either by using having the script place a blocker building and adding a SettlementBuildingExists condition (TFT does this) - or by using a trait that is added through the traits file and which subsequently blocks the monitor triggering again (I believe EB does this, maybe RG as well).