There is no real way to defend against a DDoS attack as it is basically just a massive wave of traffic so outside of taking the servers down the servers will continue to eat that traffic. There are ways to mitigate it but often times it is just a game of waiting it out or finding the general mass source and blocking it which often catches a large quantity of users in its wake. As far as the second question... yes they could use it as an excuse whenever they like should they choose to do so.
