The distinction this section turns on is the one between being allowed to speak, being taken up, and being believed. Institutions address the first and report it as fairness, while the other two are where most of the damage is done and are invisible in any record that counts speaking time. The exchange you annotated was written so that everyone in it acts reasonably and the outcome is still that nothing changes and one student ends up exposed, which is the point: you do not need anyone to behave badly for communication to reproduce exclusion. If you found yourself looking for the person at fault, that is worth noticing before you go on, because the next section stops asking who is to blame and asks instead where you are standing, what authority you hold, and which risks you are not the one carrying.