This is a valid concern here. The strength of Bitcoin comes from decentralization without a particular group having any influence to force it against it's broader network will, so if the government holds 25-35% of the total supply, it could be a balanced tilt.
It is true that Bitcoin makes direct control hard, but miners, nodes, and users internationally may have to accept any change, concentrated ownership by powerful actors might affect incentives and raise fear, though technical attack may fali, but threats can damage market confidence and price stability.
Owning Bitcoin does not give you power over the network, this is a misconception on how things work. No amount of purchasing of Bitcoin will give an entity power to change it. Threatening to manipulate and actually crashing the market does not give you any real power other than imaginary fiat-social power. You are confusing POS networks with POW networks. In POS networks ownership of coin gives you direct power, this is not the case with Bitcoin.
It is less risky when small states holds hundreds of thousands of Bitcoin, it could add legitimacy and prove institutional adoption without overtaking supply. Rather when larger government pursue to acquire millions,then grows the risk of coordinated influence.
While there is some risk of coordinate influence, it is much less than it is usually portrayed. Most governments can't agree on anything sensible within themselves or across countries. The times where they actually agree fully on something complex is rare.