I agree with your reasoning of the 250+ events statement. I believe that it was clearly stated that dosing would continue until 250 events were reached which might result in more events after dosing cessation raising the total number of events to maybe 270. Of course, nothing would preclude them from changing plans but I believe it was clearly stated that their intention was to stop dosing when 250 events had been reached.

It was stated by DM that they chose between this and ceasing dosing before 250 (eg. 230 or so) and letting it run up to 250 events but they chose the option to dose until 250 was reached.