Personally, if I saw a passenger in distress, I would have approached them and asked if they needed assistance. The OP makes it sound like they already decided that the staff member was to blame despite them not being aware of all the facts of the matter.

If the passenger in question was approached and additional assistance (from other BA staff) was sought, then the issue (if it even was an issue) may have been resolved there and then. But standing back and then posting about it on a forum isn't going to do a lot I suspect.