Either the talk was cancelled because something did happen. OR it was cancelled because something didn't happen.
So we must look at other info:
1) History of cancelling place holder talks
2) General Title of Talk
3) Statements from DI about this specific cancellation
4) I'm sure other points could be added
DI has commented on placeholder talks before and this time the placeholder excuse was not used. Even though "all hands on deck" and "finish line" are his fave phrases, they were used as opposed to a placeholder comment.
Coupled with the General title of the talk, personally I'm leaning towards something did happen to facilitate the last minute cancellation