I once got a phone call from the school to say that DS was distressed he'd forgotten his lunch. I replied that actually he'd forgotten more than this, he'd forgotten the day of the week and that he has hot lunch on Fridays 
The office said that they would always feed a child, regardless.
My DS has forgotten his bag/lunch a couple of times, he had hot lunch and it's fine.
I can't believe how awful your school is OP, this should absolutely be stopped.
Put in a letter of complaint
it's not the lunch per se, it's the attitude. there is no job too busy where someone can't spare a few minutes to drop a lunch box to a 9yo. Shame on them. The fact your child is petrified of being punished for forgetting something is deplorable.
No wonder they monitor social media, they know they are a crap school with lots of people with good reason to complain. perhaps if they devoted the same amount of effort to being kind and effective rather than focusing all their attention on maintaining their reputation as a bunch of jumped up bullies, they wouldn't need to worry about comments.