But that's good for the GGP's argument. Going down means they extracted maximum value from the market. It's a very successful public offering by GGP's metric.
What do you mean by "going down"? The IPO price was the IPO price. If people are unable to trade during the day and the price is unchanged, it just means that the stock didn't have an opportunity to trade up.
But Facebook didn't trade at a higher price when there was no longer any trouble. Nothing material changed about Facebook in those few days. So either the price would have gone down (meaning Facebook did the right thing), it would have stayed flat (same here), or if it would go up, it would go up when the exchange fixed their trouble (it didn't).
Nothing indicates that this went poorly for Facebook. It seems to indicate the opposite.