The expectation to privacy and the admissibility of the evidence is closely tied together. The problem here is that I would argue that a reasonable person would

The expectation to privacy and the admissibility of the evidence is closely tied together. The problem here is that I would argue that a reasonable person would not expect that his or her conversation in "hushed voices" (from the article) would be recorded by the normal security cameras located in the public space. Without knowing the details, it's really hard to say, but it sounds like this was a very targeted operation more similar in nature to bugging the home than to a general purpose security camera catching a glimpse of someone on the street.