Their population problem is apparently bad enough that the bodies of their population are pressed up against the sides of their Enterprise facsimile as well; that they were able to construct something of that size and complexity but couldn't keep half a million pedestrians from sitting on it tells you all you need to know about the nature of their population problem: the people of Gideon are as numerous as cockroaches and probably just as prolific. That, plus the fact that their best option is to introduce a pandemic among that seething population, tells us this is no ordinary "overpopulation" issue. It just reinforces that when Hodin says his planet is encased in a "living mass who can find no rest, no peace, no joy" he is not exaggerating much. Except you're perfectly aware that conditions such as these did not exist in the overwhelming majority of American and European cities and do not exist there now; nor have they been common to nations and regions that were NOT heavily urbanized, nor do they persist OUTSIDE of urban population centers. You know all of that. You're just being contrarian.