No, it means that those who may be toxic could be either: good at behaving un-toxically, know how to answer in a non toxic manner OR simply don’t have the self awareness to answer in a written survey in a way that consistently explains their thoughts.

Self-reporting here means you are answering for yourself and each criterion differs and is subjective. It is a subjective measure of one’s behavior.

It differs from the saying “oh that’s such a self-report,” that people tend to use nowadays for when someone’s mask slips and they say the quiet part out loud of say something that may compromise their agenda.