Interesting. I personally support Universal School Breakfasts / Lunches but what the Republicans want to do here isn't quite as heinous as the headline would have you believe.
You can read the RSC Budget here (PDF Warning) and can find the School Lunch thing on page 34.
What Republicans want is to eliminate CEP in order to force Means Testing for Free / Reduced School lunch. Government Auditors have apparently found a fair bit of fraud in the program and in this case fraud is people who are outside the financial guidelines who have lied about their income in order to get free or reduced cost lunches. The School Districts are complicit with this because the more students they have on the free / reduced lunch program the more federal money they get. You can a lot of that info from the in document citation number 144 which takes you here.
I was surprised to learn that the Department of Agriculture, the Federal Agency in charge of School Meals, spends more than 20 Billion dollars a year on this! There's a great non-partisan Congressional Report on this that you can read here. (PDF Warning).