Long-time lurker, first time poster.
First off, my thoughts and prayers are with those in Paris. To me, at least, a figure skating competition seems somewhat trivial in comparison.
Second, it seems to me as though the final results must be based upon short program scores. In all other sports, if the competition is suspended for whatever reason, the final result is based upon results to that point. American football immediately comes to mind - I can think of games that have been suspended due to weather; the final score was based upon results to that point. In terms of tie breaker for the Grand Prix final, use short program results as tie breaker. If all Grand Prix competitions from this point forward go as planned, all competitors will have had the same opportunity to compete their short programs.
In terms of fairness, in my opinion, this is the best plan. For those who argue that the long programs should be held at another time, this gives an unfair advantage to the TEB competitors in that they have a longer break before competing their long programs, and it gives a disadvantage in terms of money. Can you imagine the craziness of having a long program only event and put the burden of travel pay on the competitors? It would be equally difficult/challenging to add these same competitors to another Grand Prix event and expect the competitors to suddenly come up with money to pay for travel, let alone arrange for travel visas. You cannot really use the season's best long program score for all competitors in order to determine the final standings; we do not have a crystal ball and cannot say how each competitor would perform. And, as someone else said up-thread, this serves as a lesson that you must be your best for all parts of the competition. For those who had an off day for the short program, well, that could just as easily happen in the long program - just as those who placed well in the short could have an off day for the long. Ice is slippery.
Let's please keep our eyes on the big picture. This is just a figure skating competition. And I say that as a fan that is disappointed in not being able to watch the second phase of the event.
