In my opinion, if all countries, and there are about 200 of them in the world, create state reserves of Bitcoin, then we can get a decentralized system of storing and mining Bitcoin. This system will be strengthened by contradictions between different countries and contradictions between different political blocs of states.
I think this is indeed a good point. If Bitcoin reserves were more or less fairly distributed between the states and "blocs", I think the vision of Bitcoin as a reserve currency is a little bit less scary. The ideal for me would be indeed most countries or central banks holding some small reserves, but totalling not more than a few millions (2-3 M).
However, in the case the reserves get bigger even widely distributed BTC would be problematic. Just again citing the case of FATF involvement: China is an active member of that organization, even if the CP may have interest to hide cryptocurrency holdings or transfers, "officially" it supports anti-privacy policies (and in addition China is one of the most surveillance-ridden states of the world). Russia alone is too small to counter the whole FATF camp, and I wouldn't also like the "privacy camp" to be representated by a brutal dictatorship whose only interest in Bitcoin is warfare (a post-Putin Russia without imperialist ambitions of course would be totally okay, but then the reason for the Russian anti-sanctions stance would wane away probably). And North Korea as the "defenders of Bitcoin freedom"? C'mon ...