Oh, I definitely agree that it's Unity-inspired, and that that's canonical/explicit in the text! Yes, for sure. But I don't see it as separate from the nature of her vulnerabilities regarding failure and perceived demotion and so on in other books, even though it is more complicated -- I guess that's what I'm trying (ineptly!) to say. She overlaps with Peter and Nicola more than is perhaps immediately apparent, but they're more truly stoical, I'd say: Ginty really is (even when she's not putting it on for Unity) a bit more sensitive and flighty and neurotic,* even though she's not actually afraid of the sea. Her approach is more of an avoidant one, as opposed to the 'tougher' attitudes of P and N.

*as well she might be, after the double trauma of the bombing and TMTT?