Reading the text logically it says an order of resolution - move first then attack. Thats the way Ive always played it.
But Im not Xotl so my answer isnt the final one.
Another way to arrive at the same answer: if we allowed people to fire and then move (as I read the OP's question) would that provide perhaps too great a benefit? I can see how people might be able to use CI in those cases to cause the opposing force to lose a unit and then move completely out of the line of fire: which isn't how the rule has played out in my experience.
Normally when you use CI, you are trying to remove some damaged (or light) units from the board before they get a chance to fire. In return, your units are left exposed to counter attack. CI is already a
very strong ability in this form. If you could fire and then move out of the line of fire, this might make it a tad overtuned. I've used it in my last 3 Alpha Strike matches, and while I'm no authority, I think this interpretation would make it a little OP.