Clinton is utterly oblivious to this, which is par for the course being Clinton, but....
It appears to me that ms. Snarky Waitress is to some extent flirting with him. At least she's being sympathetic, complimenting him on his honesty instead of making fun of him, empathizing about 'caveman instinct' instead of ridiculing it, and considers it worthwhile to see whether or not he's got an Asshole Reaction to the 'pity/sympathy' thing. And offering somebody a milkshake, instead of just quietly observing and/or gossiping with someone *else* about him out of his earshot, means she is being pretty straightforward about personally getting his attention.
This combination of things ... I wouldn't make assumptions, as such, but if I were Clinton I'd be at least considering the possibility that she might be flirting with me. I like what I've seen of her so far and I'd at least be trying to find out more about what kind of person she is (and whether she's single). If she makes a point of volunteering the information that she's not dating anybody in the next couple of strips, there'd be no doubt.
And I don't know how Clinton measures attractive, but for me -- tall, healthy, fit, confident, snarky, got real curves -- daaaang, dat works! She reminds me a lot of the woman who became my wife.