I'm not sure I fully understand your argument to be honest, especially as it translates to the current conditions.
Are you saying that individuals should hold a variety of currencies, both traditional hard monies and cryptos other than Bitcoin, because if everyone converged to holding Bitcoin only then it would be easier for authorities to fight it?
I can see how it could be more desirable for authorities to target Bitcoin if no alternatives existed, but I don't see how it could be easier. How would they go about removing the 21M cap for example?