I don't really see what encryption gets me over deleting the events. The end result is the same - the event log is unusable for replaying this particular projec

I don't really see what encryption gets me over deleting the events. The end result is the same - the event log is unusable for replaying this particular projection. Why take on the extra complexity of adding encryption? Immutability is just a means to an end. It has no value on its' own.