An interesting study using a new approach to anticipate possible solutions to the Fermi Paradox. Despite our love of interstellar empires in films and literature the distances required to be covered makes suck empires extremely unlikely. As a result, while sentient beings able to move to other stars in almost certain, their ability to maintain reaches of our galaxy under their control is not likely.
We’ve been buy looking for only a few decades. Their could have been other sentients that visited Earth fifty million years ago and simply passed on or died out in this region of the galaxy. We will run across their technosignature eventually.