I've seen that scene interpreted two ways.
The first interpretation is that the writers wanted to imply a romantic relationship between Albus and Scorpius to draw in viewers interested in diversity of sexual orientations, but not make it explicit for fear of alienating anti-gay members of the audience. In this interpretation, it's essentially a snide and not very funny joke (in-universe) about Rose being jealous of Scorpius, and an attempt (out of universe) to not have the characters be explicitly gay. Again in-universe, it possibly functions as a way of Albus affirming his (putative) heterosexuality: "I know we're hugging and all, but you've got a girlfriend, so we're all straight here."
These criticisms have sometimes been placed in the context of Dumbledore's sexuality being implied, and in particular the scrapping of plans to give him a boyfriend in the second Fantastic Beasts movie.
In the other, Scorpius and Albus are very unfamiliar with social norms, as evidenced by their previous awkward hugs.
In this interpretation, Rose is more knowledgeable about the social norms surrounding hugging, and since she's maybe interested in Scorpius now, he should ask her for advice.
Of course, these interpretations aren't entirely exclusive. It's possible that the writers intended for Albus to be asking Rose for his advice because of their relationship, and also wanted to make the characters "gay but not too gay."