What are you talking about? You were babbling about it being impossible for sex to take place in a crowded room, and then trying to claim that such rooms categorically didn't exist. Obviously they did and do exist, and there's no requirement for them to cover the entire globe in order to defeat your argument.
If people with a basically empty planet available to them (us Earthlings) have sex in crowded rooms as a matter of routine, there's no particular reason to think the Gideonites who don't even have a choice would find the practice in any way inconvenient or abhorrent.
A lifestyle encompassing the busy streets and jam-packed dormitories of a big Southeast Asian city along with the penthouses and golf courses, and just omitting anything but
the confines of the city, would be both plausible and interesting in human terms already, without throwing in any alien psychology or physiology. What would stretch the limits of plausibility would be the logistics of such a Trantor- or Coruscant-like world, especially if it categorically refused interstellar interaction.