Because that's the time and we've waited until past 7pm for people plenty of times before. I'm not saying that we should do that, but waiting until the given start time and then deciding if the race is happening based on the number of people is the proper thing to do. The way trobes was telling me made it sound like people started filtering out of the room before he closed it too.
Oh, and
@trobes29, I missed your post at the top of this page until now, but I wasn't meaning text me. I was meaning make a post to everybody in this thread or send everyone registered for the series a PSN message before you close the room that simply states the race isn't happening.