>

I’m not sure that this is a huge deal like you think it is, NASA uses incredibly old hardware designs because critical infrastructure needs to be tried and tested and reliable. Granted they have the difficulties of increased radiation from space to deal with, but still even on the james webb telescope launched semi recently a processor released in 2001 was used. Granted I know almost nothing about flight infrastructure/systems
Not surprised. That’s why you use a test environment before implementation. On something as big as the FAA probably roll it out in parts too. >

That's not fair. They had a test system.
They just didn't have a separate production system. >

In every company I've ever worked for I always ask if we have a clone of production for testing.
Only once have I been told "yes".
Every other time, I'm told that the QA environment is "close enough". >

Until it isn't.  But why spend money doing something useless until it costs you millions of dollars and/or customers? >

Why wouldn’t you just make a new copy of the production environment and overwrite the QA environment with it so you have a test system that is up to date to test your code? >

The biggest hurdle isn't the code, it's the volume of users that exist in Prod vs in sub-prod environments.
And just straight copying prod data down isn't a great idea, because it contains PII. >

I have worked in QA for over a decade and I fully support this answer. With more users/volume comes more edge case usage. >

Also 3rd party integrations might not work in QA environment. Ideally they should, but sometimes that requires extra setup or work with the vendors. >

And licensing is usually the issue here.
3rd party contractors aren't going to take a missed opportunity to charge for the licensing for the test environment at the same scale as the production environment. >

And most companies aren't going to want to pay, no matter what the QA team says, until a big issue happens demonstrating why it's needed. >

The system is from 1993. The same year the first internet browser became publicly available, one year before the original Playstation, and three years before HoTMaiL (get it? Do you get it?).
How old were the contract employees? Old enough to even remember 1993? Were they even born yet?
Even a dev who was experienced in 1993 has spent the last 30 years learning and adapting to the evolutions in technology. I challenge anybody to go to work and do their jobs with Office 4.0, or operate their computer with MS-DOS. Even if you're old enough to have been expert at it then, you certainly would struggle with it now. 
The issue isn't the contract employees. The issue is that our government has been trying to repair our critical infrastructure with 10,000 band-aids, and if even one of them falls off then our economy starts bleeding to death.
How many of our other critical systems are literal antiques that could break at any moment? Does anybody have the skills to repair them anymore, or are those people all in nursing homes by now?
Do I even want know the answer?