From your reading, the relevance principle prescribes that an accounting information system report useful, understandable, timely, and pertinent information for effective decision making. Why would information need to be relevant?

Knowing the cost of a rocket to the moon probably will not help you with the choices you need to make in your hamburger flipping business. More likely, you will want information about costs and revenues associated with hamburger flipping.

Irrelevant data is just that:

irrelevant. It has no value with respect to the questions at hand.