At some point the US government required ADA for all new development.

Yet here we are.

ADA is still the law, but, yes, Ada the language was mandated for 5 or 6 years and everyone got waivers for it anyways.

A big difference between the Ada mandate and this current push is that the current effort is not to go to one language, but to a different category of languages (specifically, "memory safe" or ones with stronger guarantees of memory safety). That leaves it much more open than the Ada mandate did. This would be much more palatable for contractors compared to the previous mandate.