Governments want secrecy and control.  Monero and fiat are similar in that regard. By using fiat governments retain both. They will never choose monero because it is inferior to fiat gor yheir purposes.

The reason governments are buying bitcoin is because game theory is forcing them.

If fiat was not an option then corrupt institutions would prefer monero to bitcoin to obfuscate their criminal behaviour.

One thing criminals don't tolerate is competition. They have no sense of freemarkets because free markets are morally ethical. Fiat monopolists won't tolerate monero as they won't tolerate a moneyprinter in your basement.

Bitcoins ethics forces governments to play nice otherwise they look like dictators when they ban it putting them in a hot seat with their constituents.

Bitcoin forces behaviour where monero obfuscates action.

You decide which is superior and allocate accordingly.