You are misinformed. 217k BTC is only a fraction of the monthly volume traded on some of the largest exchanges: they trade 3-6 million BTC per month (http://bitcoinity.org/markets/list?currency=ALL&span=30d), so one could trade 217k spread over 30 days without causing swings. (Only if you did the trade at once, it would cause one sudden swing.)
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Does bitcoin have the kind of volume/liquidity to make that kind of exchange without causing a significant disturbance in the exchange rate?
No, it would cause a pretty big swing. Large sums like this are unlikely to be put on an exchange, though - they'd be done through a private sale.
You are misinformed. 217k BTC is only a fraction of the monthly volume traded on some of the largest exchanges: they trade 3-6 million BTC per month (http://bitcoinity.org/markets/list?currency=ALL&span=30d), so one could trade 217k spread over 30 days without causing swings. (Only if you did the trade at once, it would cause one sudden swing.)
Dumping it all at once is what I had in mind.
Well, I wouldn't expect someone to try cashing out such a large sum at once. I assume they'd just cash out a few thousand here and there as needed.