I understand the objections to making use of BTC compulsory from a libertarian purist perspective but this is an essential aspect of making something legal tender and is a core expression of national sovereignty. This indeed is why it is such a monumentous development.
Nation States get to choose which currencies their people must accept (but do not get to constrain those currencies their people may accept).
To do away with this fundamental right of a Nation State is to do away with Nation States altogether.
I know that this what libertarian purists would like but there is currently no alternative (as much as I would like there to be).
Humans are fragile physical beings that require the security and safety of the group for survival (especially of their vulnerable young). In the age of modern weapons the Nation State is the smallest group that can provide this protection.
You confuse exclusive legal tender with legal tender.