I think you mean if they steal it. Mtgox today became officially Verisign secured, so it's approximately as secure as any other site on the Internet.
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The investors are free to come and go as they please. They can set their bid prices at any point they wish. They aren't required to agree to anything.
Verisign secured as in they have an https/ssl certificate? Or is that some kind of third party penetration test? Either way It doesn't mean a whole lot as many users are hacked on their end as well, and more sites like mybitcoin will popup and steal coins forever, it will never stop (until bitcoins are worthless). So WHEN not if, coins are stolen, an artificial price will maximiize their profits, instead of crashing the value like what should happen when a huge dump on the market occurs.
The second quote makes no sense to me. If people are setting whatever prices they want, then you are describing the current system, not an "artificial wall value" system.