Sherlock season 2 episode 1 Why was Irene killed by terrorists? Why did she send that message to moriarty?

Irene does not belong to any party. She knows the secrets of the government and terrorists. Besides, although she cooperated with moriarty, she has already lost. She fell in love with Shylock. No one knows whether she will surrender to the government for this. In addition, the terrorists who want to kill Irene are not necessarily people who want to prevent bombs. Irene is not a terrorist. She just had these things, and then she went to moriarty without knowing how to use them. Naturally, she can also go to the government to deal with terrorists. They won't rest assured. So she must die.