but as that Dallas chap observed adoption as a currency is negligible, so they see no reason to interfere
Yes, so all of the bluster to date about central banks stamping out bitcoin have been just that, bluster.
Only if there is consequential adoption of bitcoin as a MoE will CB's and governments feel compelled to intervene.
But as stated before, in my opinion, bitcoin will only ever be adopted as a MoE when the prevailing economic circumstances make it more beneficial to retailers and consumers to use it rather than the existing fiat currency. Those circumstances, generally speaking, will involve a sustained period of instability in the existing currency, combined with a significant section of the population already holding bitcoin.
For example, imagine if somewhere like Greece decides they are out the euro, in turn, causing a chain of events, unintended, that destabilises the euro.
Or, as the repercussions of Brexit take hold, other European countries follow UK and exit it out of the EU heralding a chain of events, unintended, that destabilises the political and economic environs of Europe.
You may consider such circumstances as highly unlikely or will never happen, or more apt from your outlook, will "never be allowed to happen".
Im a bit more circumspect, and my outlook is that no-one knows what will happen, other than anything can happen.
As it stands, as bitcoin price climbs higher and higher, it is signifies to me increasing interest in bitcoin. More and more people holding bitcoin. But as you say, if it is not in use as MoE then CB's need not fuss themselves over this.
But if a sustained period of instability and volatility were to emerge in the CB issued currency, then retailers and consumers will move to use alternative means to exchange goods and services if it is in their clear interest to do so. At which point, it may be too late for CB's and governments to intervene.
It may never happen. Cb's and governments may restore European and global economies and monetary systems to rude health and momentum for bitcoin may diminish.
On the other hand, Europe of all places is, historically speaking, synonymous with instability.
I just think at this stage it is wise to hold some bitcoin, for whatever happens.