The most horrifying aspect of the hypothesis as depicted in the Dark Forest book is that it was simply the job of a low-level bureaucrat to identify "low-entropy entities which lack the hiding gene" within their region of the galaxy and allocate a basic bottom-shelf munition to "cleanse" it.

However, humans were aware of this possibility and had spent centuries reorganizing the solar system to have a measure of resilience to it. So, to humanity's great credit, he had to go get permission from his supervisor for to deploy a next-tier solution.

"Why would anyone travel across town (i.e., the galaxy) just to step on an anthill?" We have a whole industry dedicated to exterminating any other life that invades "our" living space. It's considered an unremarkable necessity.