You're correct, and I should have fact-checked that rather than relying on my memory of what co-workers have said. Project 25 (P25) was started in 1988/1989; the first compliant radios came out in 2012. At some point after 9/11, it was mandated that all government radios purchased must support P25 (for interoperability), likely as a 9/11 Commission recommendation[1].
[1]: https://majorcitieschiefs.com/wp-content/uploads/2021/10/MCC...