Colt is a supplier to government standards, just like Bushmaster, FN, and GM Saginaw.
Gold standard doesn't exist - there is no milspec for that. If anything, SIG is regarded as making the highest quality assault rifles for a nations Army. I don't see the Swiss bending over backwards to buy Colts because of a demonstrated superiority.
Nations buy a specified firearm to a contract standard and accept the lowest reasonable bid. All things considered, Colt was the cheapest. That has nothing to do with a superior level of quality, just a documented level of consistent adherence to standard.
Many smaller makers can achieve higher levels of quality in their product, and do so. They can easily take the government minimums and improve the material quality, fabrication, and tighten tolerances to make a better, higher quality part. Noveske does that with barrels everyday. But, it's not milspec, because that standard is based on old technology and bureaucracy, not the quest for the highest quality. Just a minimum.
Government standards mean M4's shoot to 2 MOA. That's run of the mil on the open market. Milspec also means 6-8 pound creepy triggers, another low point. Milspec currently accepts 3000 round barrel life. And milspec means that Colt's just meet minimum standards, just like toilet seats.
If there is a gold standard, please specify where it is spelled out. The nature of the competitive bidding process pretty much eliminates any one offering it.