I think he mentioned they didn't want to do surgery because it was too risky.
Well, that would imply that it's not too big yet. They wouldn't operate on a small one if the risk of it blowing out is less than the risks posed by surgery. That's why they usually wait until it reaches a dangerous size - UNLESS he is symptomatic, or has Marfan's or some other connective tissue disease, or a family history of aneurysms etc.
For instance, a small one has less than a 4% risk of blowing out in a year. If the risk of surgery is greater than that, they would wait and watch to see if it gets any bigger. Nerve-wracking I'm sure. This will probably bring on a second MLC.
Since he DID go to the ER with some symptoms, though, he should probably think about getting a second opinion, preferably from an expert at a large teaching hospital.
