That's illogical, here's why: everybody 'in the know' is aware that the US dollar cannot remain forever. So if a Central Bank created BC, they would want it to look like a strong alternative to the dollar as the dollar collapses - in essence, something like unto gold which goes up while the dollar goes down (market fluctuations not withstanding). So as a CB, you would want the BC to look like a stable safe haven to get into while the dollar continues to drop which would then get more investments. That way, once the dollar dies, you already control the new currency, BCs.

Ergo, it would not be a good argument to state that BCs are controlled by CBs. In fact, I think it is the opposite; they do not control BCs, and therefore, it must be destroyed.