Completely agree with Hattie - there's a sign, and the drop is really very big at this particular spot. Really dangerous to take a buggy there, regardless of the time of day.
Lifts in stations can be smelly but certainly never felt threatened in any of them, have taken them by myself with sling, in pushchair, or with toddler.
The sign is not there to annoy customers or users it's there to protect them, or their babies. Some of the responses on here remind me of a thread that caught my eye on Mumsnet the other week started by a mother to be who was outraged that she couldn't take a babe in arm to the Chelsea Flower Show. There's a time and place for everything, regardless of whether we're mothers or not.
As has already been pointed out the commuter might well have been trying to get home to see tot before bedtime -- a stressful experience that some mothers on mat'leave are not always attuned to
I tend to think rude mothers are just sleep deprived and let it go ...