I agree it's a bit confusing that it's counted in other places, for example in the Event Host badge and in the "Placed by type" on the hides tab etc. That doesn't seem right to me and I would consider that a bug.
On the other hand there is a non-PGC way to solve that issue if it annoys you enough... You could ask a reviewer if they could retract the event for you. I think most reviewers would do it as long as you just ask nicely. If the event is retracted Project-GC doesn't know about it anymore and it's out of your stats. :)