What if the reason she was "singled out" was actually that she was the only person the swearer didn't know well enough to feel OK about swearing around? Or was the only one he considered to be in earshot? Or she was just the closest and he felt he should make some gesture because he regretted it, but it wasn't bad enough to personally apologize to every last person?

I guess the author's impression trumps ours (and only the swearer's honest account of his thoughts could trump hers), but she didn't really address those, so I have some doubts on whether it's as clear-cut as you say.