Bitcoin cannot be used as a bully stick to oppress the citizens of a society, unlike fiat can be used. If you use your bitcoin, that's it, it's gone.
Bitcoin only benefits net producers. It punishes net consumers. A government that has a bitcoin reserve will either become a net producer, globally, or will not hold it's bitcoin for long.
The US government cannot "borrow against it's bitcoin" to somehow gain power over other people and nations. It can only spend it's bitcoin.
You imagine that the US government will give it's strategic bitcoin reserve to china as a custodian, who will then lend the US dollars, and the US will be a net producer with those dollars and eventually pay off the loan and get their bitcoin back from China? That doesn't make sense.
If you are a net consumer bitcoin does you no good. But any government that buys bitcoin is good for global adoption. Especially the richest country on Earth.