As Noguchi walks away from the girls he overhears them whispering something. The narrator says:
And then, even though they expected him to be five metres away, he stopped.
I'm confused by the use of は in this sentence. It doesn't seem to be marking a topic (5 metres would be a strange topic). It doesn't seem to be marking contrast (5 meters compared 4.2 metres, 9999 metres etc would be nonsense. Furthermore, the girls expectation that he be exactly 5 meters away is also silly.
I'm left with the conclusion that this は must mean 'at least', or that I've hopelessly misinterpreted the sentence. Am I correct? Can you provide other examples of when/how I should use は in this way?