Author here; I'd love to get some discussion around the topic, as I'm sure someone else must have thought about this, or comparable issues with other systems.
I was thinking one way would be to hook into Elasticsearch's events and trigger some custom script upon deletion that would find relevent documents across nodes and overwrite them in the segment-files or some such, but as I haven't had the chance to look that deeply into it yet I don't know how pratical this solution would be.