Perhaps the most odd situation in the Dreamstasis Multiverse is that aliens are so rare. The reality of course is that aliens would be rare. In Dreamstasis, most of the known worlds are in a small chunk of the Milky Way Galaxy, so while the Drake equation might suggest many alien species, the vast majority exist far, far away such that the vastness of space makes ever meeting them unlikely.
Furthermore, most of these species come into existence at very different points in time, such that their developmental levels are far different from our own. Of those near enough to study, most are still in the billions of years of evolution before sapience and civilization. The rest are thousands to billions of years ahead of us, such that they have the technology and moral development to remain hidden and avoid interfering with the development of other civilizations except in extreme circumstances.
It should also be made clear that any civilization that develops to the extent that time travel is a possibility is bound to send back guardians to safe guard its early development from interference. As such, that the Alien Nation are encountered so soon in Dreamstasis is arguably an aberration from the norm.