the joint did make his concerns known prior to the distribution of the winnings. It can be argued that the timezones prior to the standardization announcement should have been based on the user's local time, as shown in there profile. Because of this confusion, the distribution of the funds should have at least been brought into public opinion after his announcement of his ruling, but before the funds were distributed.
That being said, this was a free contest, and nothing about the rule change reduced the joint's chances of being correct. Thus, I don't think that it really matters how this should have been handled. It was handled, and not in an unfair manner.
Maged,
Your statement that "nothing about the rule change reduced the joint's chances of being correct" is irrelevant, and instead, it should be "nothing about the rule change reduced the joint's chances of
winning. You must keep in mind that there was an additional rule as stated in his OP that stated in the event of a tie, the winner would be the first correct guesser. Now, Goat and I tied in the sense that we guessed the correct date according to our corresponding time zones. But, since I was apparently allowed to change my guess under the rule change, it then became impossible for me to win. I could no longer pick Dec. 20th, the selected winning answer and Goat's answer, because my guess would be instantly nullified since he had already guessed it. Thus, the rule change itself meant that I not only had reduced chances of being correct, I had no chance of winning.