That would indeed become agreeable (even if still not super-nice) if they changed the cancellation form to a two-option choice between "delete all private" and "publish all private".
A third (perhaps more sensible) option would be for all private presentations to be retained, but presenting and editing them is disabled. Downloading them can also be retained. If the subscription is renewed, then they can easily switch back on the ability to present and edit the private presentations.
