I imagine that, out of everyone involved, Lavi wouldn't believe this. I mean, for how late she appeared, and everything that has happened, it is the most stupid deduction to think that Philo would willingly give items, and keep them, to the one person who's close to the owners of the skills which they house.
I can't believe that Lavi's first train of thought would be that one, and obviously Lavi's sister opposed that conclusion at first blush. Maybe for his father and for the guild receptionist, who don't know her well, and for the other people, who don't really seem that interested in her.
But if the author really makes ALL of them fully believe it...it would be actually frustrating.