I think you are on safe ground if you cite sources that are publicly available to anyone who cares to look. When people post on social media it's a form of publishing. Sorry, I'm not sure what you mean by 'Sarah Fan Club' or 'comments section on the PT'. I can't find anything on AirW's FB account. Where did you see these comments?
What I have seen from AW's FB, and everyone else has probably also seen it before me, is that BW was picked up by SW 9-11am on the 18th from her grandparents after going for a stop over the night before, and that he was the last to see BW.