I realized the linked post about a very complex technology in an article is intended for a general audience but even by that standard it is very confused.
Chip scale atomic clocks have been commercially available for 20 years
https://www.nist.gov/noac/tech...
and continue to improve in accuracy, durability, and reliability. Reading some of the commercial supplier listings to the point just before they stop and say "DOD customers call your sales rep" it appears that there are CSACs designed and qualified to be fired inside artillery shells so I think we can conclude they can be made pretty tough.
I think the article is trying to say that what is needed is an atomic clock that would fit in an aircraft electronics rack that also has the accuracy of a cold atom fountain clock, which is the current NIST/NPL/NRC standard. To which laboratories around the world say, please, bring it on. And all the national labs have been working on such for quite a while, not only NPL.