Rest assured that all threads closed in HGSS tends to be for a good reason or three, and I would think the closing posts by I or Hirro (or in cases a higher-up) would state those reasons.
That thread... *double checks* Well, that thread had been closed by a higher-up, and rightly too for a few reasons. Questions are fair enough, but for starters the question had already been answered, so there is no need for a thread to remain open for others to repeat the same information (or in some cases supply a different incorrect answer... or even spam in - happens in such sections often and not just this forum either, speaking from experiance). Secondly it was actually against the HGSS rules in a way - because they state that any questions should be posted in the stickied Help thread at the top of the section rather that posted in a new thread. (That's there to minimise the flooding of short-lived threads that could have been answered very easily or searched for easily - basically keeping it all in the one place - another advantage is that forum regulars know of it and hence can help out people there easier too).
Basically, any question threads are either merged with the Help thread (in the event that nobody has answered and I or another mod do not know the answer either) or closed if it has already been answered/if I or a mod can answered it when closing, as that serves the threads 'purpose' and no other discussion is needed. Hope that explains that for you.