I think the discression is really up to you. Ken was trying to give you a great day out and i guess he felt the baby would be okay... it did survive the trip didnt it?
I also think the ride you took the caution sticker sais no infants to sit on the side seats of the Blue MOuntains railway as I have seen many young children on that ride. I also think the tour is not responsible it is the railway operators who would stop the child from riding if it was unsafe.
