I think your focus is on the wrong issue. First, how the SBA or OMB choose to classify businesses isn't really relevant because that is not what is being used to get around the rules and nobody said what was being done was illegal. What's being done is immoral. Second, the loophole that companies like Shake Shack and Ruth's Chris are using is that they have franchises which puts them below the threshold for being a business that is eligible based on a trick of accounting more or less used to keep their tax burdens, as well as other Federal regulations out of their business. Third, the press never said that they were using a legal definition based on how the SBA or OMB define the size of a business. They are simply reporting what is going on and using what we all commonly understand is the meaning of small business and large business. And using those terms to let us know that money intended for "small businesses" is going to "large businesses."
I just don't get the focus on the press in your original post.