I was on the Tube yesterday and the man next to me had an open packet of peanuts which he was eating. It's such a common allergy and I know quite a few people, including my own brother, who would have had a serious reaction if they had been on that Tube.
Should I have said to him he shouldn't eat peanuts on thevTube even though I would not be impacted because I was worried about other potential sufferers in the carriage, as it's a very confined space and it was rush hour.
AIBU - It's a free world
YANBU - peanuts are a very common allergen and people should not eat them in confined public spaces.