There is no way I would ever trust that one or even keep it. Sig would now be a dirty word to me. There is no excuse for selling something especially a gun with those kinds of problems. I would officially write Sig off in the future. That is just me though. I have a low tolerance for low quality.
IMO, that is a little overboard, especially if it's his first and only Sig. If I lived by the same standard, there would be a very limited selection of guns for me to choose from. Just to give you an idea, here are some of the guns I own or owned at some point and needed to go back to the factory..
Sig 239 - FTE's, broken roll pin. Both replaced on Sigs dime and I'm still carrying it to this day. Nary an issus since.
Kahr CW9 - Extractor and firing pin issues. Kahr fixed it, I sold it.
S&W - 637, cracked hammer, misaligned barrel. S&W replaced the frame and it's now my EDC.
Walther/Uramax P22 - Too many issues to list. Replaced by S&W or whoever runs the show. Sold by me shortly after.
Glock 26 - Extractor issues. Repaired by Glock and sold by me shortly after.
Springfield Micro - All kinds of issues. Replaced by Springfield, sold by me.
Taurus Revolvers - Quite a few and they all had issues. I have none left and will never own another.
Kimber Ultra & Pro - All kinds of trouble, multiple trips back but issues never resolved. Both sold with full disclosure and at a huge loss.
That's a pretty good sampling of the major manufacturers out there, although I still have not given CZ a chance to screw me. In due time, there a few models I've always liked... Anyway, despite all those issues, the only ones from the list I consider a "dirty word" are Kimber and Taurus. Why? Because the product they sold me was not worth the price and the customer service was awful.