It was just a natural wonder about the situation. That is, I wondered if .... etc. Been in a similarly hairy situation myself, baby under one arm, dropped the buggy I'd lifted off the bus, turned to give two year old a hand off the bus and saw that it was moving and the doors still open! I've never yelled STOP! louder. If it's judgmental to think the bus driver was possibly at fault (they have mirrors to prevent this kind of thing happening), then I'm judgmental. Fortunately people on the bus acted quickly too and rang bells, shouted, etc.
As if I wasn't stressed enough catching two buses across Edinburgh to take the four month old to hospital for a hip x-ray. So, yeah, I know how easily accidents happen. They can often be prevented by carefulness.
Which is not the same as looking for someone to blame.