I agree that the fuel temperatures were low, I am not flying the 777 so I don't know what the minimum fuel temperatures are, as such I cannot assess whether the decision was timely or not.
Obviously there would need to be a valid reason for continuing flight at the planned level if the temperatures were below limits. Again, that is information to which I don't have access, only that the crew were not held to account for such a decision as far as I recall.