It was a metaphor, here I'll explain it. The singularity is something in the future. Some believe the singularity will be an entity smarter than humans, that can do things, including move, perhaps even move itself in time. Who knows? Thus the trotting use as an anthropomorphic description of singularity behavior.

Furthermore, as technology progresses, the date at which the singularity will arrive is getting closer and closer, thus the singularity is moving backward in time, from the future to the present.

So humanity and the singularity, in a plane beyond the space time continuum are moving toward each other, humanity moving forward through time, and the singularity moving backward through time.

It's just poetry. That's why jderick said to use your imagination.