When Justin meets August for the first time, he's surprised. He thinks that he shouldn't be, given how much Via has talked about him. Justin shakes August's hand and tells him about zydeco for a minute before Via leads him out of August's room. Justin explains that he and Via have been dating for two months now, and he liked her from the first second he saw her. Via told Justin about August on their third date, and he noticed that she never used the word "deformity" to describe him.
It's telling that Via strongly rejects the word "deformity" when referring to August. By rejecting that word, Via tells the world that she believes there's nothing wrong with the way that August is—although he's different, he's not different in a bad way. This allows her to both stand up for him, as well as recognize a part of August's identity that he doesn't like as something good and worth celebrating.
After Justin and Via get to Via's room, she asks what he thought of August. He assures Via that he's not shocked, and Via explains that when she was a kid, lots of kids never came back for a second playdate. She says that they weren't even being mean; they were just scared. Justin assures Via he's not scared, but isn't sure she believes him.
Via is clearly trying to test Justin here; her implication is that if he can't handle August, he will no longer have access to her either. By doing this, she insists to Justin that their relationship is contingent on his genuine kindness—which also offers another incentive to being kind.