Or even if pax▸ had remained seated until the train came to a stop?
Pax are their own worst enemies quite often
Only passengers in high-backed rear-facing seats would gain much benefit from remaining seated. Anyone else will be carried by their own inertia until they are acted upon by an external force, e.g. a stanchion or another seat.
"An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force."
Newton's First Law, innit.