Assuming the police know what they’re doing may be your first mistake.
Samantha is a transwoman. That is very obvious. So obvious that one of the resident TRAs didn’t hesitate to identify Samantha as trans, despite the fact the police hadn’t mentioned it. The police could have said ‘missing person’. Saying woman and accompanying the notice with a picture of an obvious male person unleashed some quite unpleasant transphobia on other social media platforms - actual transphobia- and may have been avoided had they framed it differently.
In addition, the latest photos suggest Samantha was no longer presenting in a particularly ‘female’ way. As @GreyskySexRealistsky points out, it is highly likely that the person sitting next to Samantha on the train would think they were just sat next to a man. Why would they consider the search for a missing woman relevant to them?