The edges on SA factory guns on smaller parts are pretty well known to be a little on the sharp side. In all fairness these are standard production guns, not semi custom or custom 1911's. The slide release on my SA Mil-Spec back in the day was like a razor. I took a patch and a little flitz polish and smoothed it out in 2 minutes and was not concerned with it.
I understand your frustrated but the edges on a barrel bushing would be the least on my worries on a standard production 1911... not trying to be snark either. Unfortunately we don't live in a day where every gun is hand fitted, and raw materials are a lot more expensive, so corners ARE cut to keep the consumers happy. I can refer you to a hand built Wilson Combat 1911 with a rail or any other custom shop build that would cost 3-4x as much as your SA.
It sucks you got a lemon, I can relate on that, but least they are willing to refund you the $$ since they cannot keep up with current demand. That is a lot more than most other gun mfg's would even do.
I know you probably still aren't happy with the outcome, but I think they are trying their best for you. Though I can't comment on what happened when it was in for repair, I have never see a gun come back from SA to my shop with anything wrong with it.