It's probably worth pointing out that central banks very often resort to major manipulation to keep their currencies nicely aligned. Good examples would be Switzerland, who announced they would print money and sell it to stop the Swiss Franc strengthening, and the UK struggling against Soros to stay in the ERM.
Reserves are measured and used in multiples of billions.
There is no reason why they wouldn't resort to such tactics if Bitcoin became a concern.
Bitcoin would only become a worry if it's market-cap became much, bigger. $200M is jolly small. For a paltry investment right now (buying bitcoins) they could place themselves in a very strong position later to seriously manipulate the price.
If a central bank allocated as little as $10M to taking a strategic position in Bitcoin it would
a) be tiny as far as the bank was concerned
b) form a significant part of the free-float of Bitcoin, allowing serious manipulation.
This is not the whole picture though. There are many, many entities (and individuals) quite capable of taking such strategic positions : Ebay, Google, Hedge Funds , high-net worth investors. My guess is that averaged out, such folk would want to bet on Bitcoin's success, rather than failure.
At $200M market cap, no-one (or very few,who can afford to massively dump) have strategic stakes.
If Bitcoin is going to be a winner, it will increase in value significantly, this entails silly bubbly-growth and the ensuing volatility.
I don't think anyone has seen serious volatility yet...
If I was a worried banker, that's how I would handle it. But you are right, I'd bet on success.
