Obviously Dalene failed to follow policy, but I don't think it's right to put a minimum wage lunch lady on the front lines of taking a student's tray away and dumping it (school policy, according to Dalene). If reports are accurate, who could look at the senselessness of the policy (the food is going to be thrown away anyway) and deny a hungry student that food.
Food being thrown away isn't a great reason, otherwise who would ever pay for a meal ever again when you could just wait and say, "Oh, well, if you're gonna throw it out anyways, might as well put it to good use."
The money to pay for the school lunches has to come from somewhere, so either you increase taxes to cover additional expenses like school lunches or you make the parents pay for their children's lunch.
Obviously there are cases where indigent parents cannot pay, and most school systems I've ever known offer exemptions in the form of some free lunch program which is covered by taxes.
I don't think I would have fired her, but it is reasonable to assume she should at least have the incident documented in her file and, should it happen again, then be fired.
"Reason obeys itself; and ignorance submits to whatever is dictated to it" -- Thomas Paine