I think the quote is also erroneous because it assumes that all of those coins could be sold at $17 (or whatever price point you want to choose). The MtGox hack proved that it takes only a small percentage (~6% if I recall correctly) of BTC's to be sold to bring the value down dramatically.
About a month ago during the CBS interview the owner/operator of Bitcoin Watch said the same thing about a 100 million dollar market cap. Yes that's assuming if all the coins would be sold at ~$15 at the current number of BTC. It does take an small amount of coins to move the market, more the reason it would be simple to let go a few here and there each time the 100 million cap gets broken to bring the market cap in check. This would create stability to an extent and also give the big players capital to buy up coins should the market start to fall again helping maintain the balance and cap. Watching the market as of late it seems a correction occurs each time the markets wonders off from the 100 million cap, we've been moving around that wall all day and working towards that mark for the last week.
I am skeptical of my own theory I must admit but I see some reasoning behind why some would do this. The stage has been set. The network has it's power, the market a substantial value and now it's time to introduce innovative and refined was and means to use this system for a larger market of goods and services all the while making more ease of use in day to day transactions. Once that phase is implemented the demand for a larger market cap will be seen. Reason for the cap now? Only to keep Bitcoin from turning into a mere speculators tool that could not be sustained much larger than the current market cap unless there is more substance and real use of Bitcoin as a currency.
