Always bad to assume gender of course, but "boi" is also often used by women with a meaning similar to "tom boy", or "butch", or just a woman who presents more masculine than average. Anyway, I don't know who the model is or their preferences, just wanted to clarify the term that was used is used by several genders, most of whom are not men.
And many women find being referred to as boi to be incredibly insulting. Especially if they are more androgynous, and it's often used as an insult against them.
And when the model is specifically modelling for the women's section of a store, is is pretty safe to assume gender. It is highly unlikely someone would model for a gender they aren't.