Workflow that inadvertently cancels all registrants all enabled events

A staff person at a client's inadvertently cancelled many thousands of registrations through the following workflow:

Disable an event with some registrants.
On Manage Events, beside a disabled event, click on one of the Participants buttons, eg http://dmaster.demo.civicrm.org/civicrm/event/search?reset=1&force=1&status=false&event=1 - note the event=1 key-value pair in url. The search results respect this parameter, but the Event Name is null, possibly because the event is disabled and it is not supported to search on disabled events for participants.
Click to select All records for the event, then choose Cancel Registrations action.
Note that the number of cancellations on the form displayed after choosing the search results action is different, but there is no other feedback that suggests a problem. The number now includes many more registrations - basically all registrations for enabled events. Confirming the cancellation will cause them all to be cancelled.

The problem extends to other actions that may be taken on the search results, such as emailing.

I think the fix needs to involve supporting searches on disabled events. Perhaps the auto-complete doesn't need to include them, but if they are properly entered in Event Name field then the search criteria should apply. If an event is in the url, then its name should appear in the Event name field. I imagine doing this should allow the criteria to flow through properly to search results action form from the first search results form.

We may want to change this to Critical priority based on its potential for significant data corruption through serious usability issue.