Another night another question

Descrated temple reads:

Action: When a [Choas] unit you control leaves play, destroy target development.

Does this force the controller to destroy their own development if there are no other developments in play? I would guess no because is doesn't say "forced" but the word "when" seems like it could be confused.

Actions are always optional, you may trigger them but you do not have to. "When …" just indicates a trigger condition, you may only trigger this action if that condition has been met, and you have to trigger it at the earliest available opportunity after the condition has been met or not at all. If you trigger it and your opponent doesn't have any developments, you'd have to target one of your own though.

Thank you, again.