Very well done. This is the decisive moment, but not because they look like they're interacting per se. The decisive moment is the moment when there's a picture there, not a bunch of stuff and people.
This is a picture, and a rather good one at that. Everything in the frame is necessary and in the right place. Nothing is superfluous.
This is wonderful - a perfectly captured moment! A beat of time one way or another would have spoiled it.
The grime and graffiti of the glass walls just adds depth. Even the window frame in the lower left helps, as it pushes the eye up to the faces. The lack of sharpness helps keep the subjects' identity to the viewer as "strangers."