This social interaction is a little goofy, why would she ask you to sit down if she’s going to be using her phone, regardless she must have had some interest IMO. I generally avoid these kinds of interactions at all costs but in this situation, I agree it’s better to take the seat and then be a dick and not take it. Some people have the capabilities to pull off a phone number or whatever and turn this into something but I don’t think we’re in the same realm as those people.