I did not have any part in the hackathon process, but I had and still do have quite a bit of visibility on how the process was run. I can assure you that an enormous amount of effort went into the judging and that it was entirely unbiased. There were literally dozens of the most senior executives and engineers within the company that worked on the earlier judging rounds behind the scenes. I actually declined to be part of that process because it was too much of a commitment for me to make. I know, for example, that the next-to-final round judges were up until the early AM reviewing the submissions and that each judge looked at on the order of 20 different submissions per rounds.
Sadly, whenever something like $1M is on the line, there is always going to be someone that is unhappy with the outcome. People will speculate and make claims that are outright false. But please keep an open mind as you read more about this event. There will soon be some official communication on this topic from salesforce. I suspect that the more actual facts you learn about the process, the more reasonable it will seem.