I feel sorry for this guy. His Reddit inbox is probably fucked, and he's absolutely going to get doxxed and hounded by news people, and I wouldn't be surprised if even worse things happened to him.

Good on him for reporting what he saw. He also went to the police the next day and reported it directly. But now the media machine is going to make him regret he ever said anything, which is unfortunate.

I think the eye contact bit is useful as a signal that the witness got a very good look at the suspect's face.

I suppose that made eye contact = the face was clearly visible for a second or two, and thus recognized with more certainty.

I think the eye contact in question was a prelude to the two of them kind of following each other around and a minor verbal altercation, so the later context shows that it was probably kind of suspicious eye contact, rather than a friendly "what's up?"

I agree with the other comments that this sentence is just poorly written.

In cities people tend to not make eye contact while walking by each other, though in smaller towns it is more common to acknowledge each other in passing.

In neither case would it be accurate to find eye contact suspicious. The sentence appears to be a summation of several things the person saw, convincing them poorly and creating the ambiguity.