This is a celebrity, right?
I mean, I've never heard of her....
Same...
In an ideal world the person causing the blockage between 2 vehicles would clear a pathway ASAP, but within a child centric venue, such as this, I think the odd hold up here and there is to be expected. Not saying that either party was right or wrong in this situation, just my view on what I read.
Having said that...
Between my 2 children they have been locked in the car 3 times

(I'm obviously a slow learner

). The first time was when DS1 was 4 months old. The absolute sheer horror I felt when I realised this was indescribable. However, I didn't start shrieking and yelling and basically making a spectacle of myself. I've also learnt that my local equivalent of the auto club can be on the scene in less than 5 minutes in these situations.
This woman (whoever she is) can't seem to make up her mind - stand back and they're judging/ignoring her. Come close and they're just coming to stickybeak. Which one is it!?
Just because they weren't all running to her aid doesn't mean they were judging and/or bullying her. I don't think that accidentally locking a child in a car is something that warrants judgement. Letting them play in traffic? Yes, I'll judge someone for that. Locking them in the car? Will only elicit sympathy, and a helping hand if necessary.
I think she is projecting her own insecurities onto the actions of other people. I've never felt, or let anyone make me feel, as though my job/actions as a mother is something to be judged.