A few details are on the AP2 site itself, and whenever J Nash or S Campbell make a website they always include the disclaimer, "And don't put this website on a CD and sell it, or something".
Whether CU shut down because of the lawsuit is difficult to say. Given its low circulation at the time, a costly lawsuit can't have done their chances of survival any favours. The proximity of the two events (lawsuit and closure) indicates a possible cause-and-effect relationship, but it can't have been the sole reason for the closure.
The AP2 members certainly did not shut down CU; they obviously did not have the power to do so. If you do attribute the closure to the AP2 lawsuit, lay the blame on the CU team who willfully infringed copyright, the EMAP legal team who allowed the release of the illegal cover CD, and EMAP itself who actually shut down the mag.