COPD is probably only associated with AAA ruptures because it is closely associated with smoking. Smoking is a major risk factor for developing an AAA, probably secondary to things like endothelial damage and promoting athersclerosis, similar to the way that causes coronary artery disease.
From what I could find it sounds like people who get COPD also tend to get AAA. One source said that a similar mechanism is at work destroying lung paranchema and destroying the aorta. So they are 2 associated but independent pathologies. But I have also read that if you have a AAA then COPD is a risk factor for rupture, which sounds like COPD is somehow increasing the risk of rupture. But I have been unable to find any source or person explain how COPD can increase the risk of AAA rupture. I guess it doesnt matter anyway.