by Dan Poltawski.
(Arguing on both sides of the fence here)
Activities are actually instances stored in course_modules table, the deleting is done by core
Is that how we will define the rules? How about adding a new course module, mod_assign. In that case we might also want to know what submission plugins are enabled. Does that generate two events? One \core\event\course_module_deleted and one \mod_assign\event\instance_added?
(Please excuse my sloppy naming).