Phil Gramm isn't going to stick up for large corporations. Instead, he tells stories about his constituent Dickie Flatt, who owns a small printing business and gets ink under his fingernails. Flatt's company is populist. General Electric isn't. There's nothing inherently wrong with this rhetorical strategy.
Small companies are a lot easier to picture.
Their budgets operate on a scale closer to the household than the nation-state. But most populist politicians don't use small companies as examples. They use them as special cases. Instead, they suggest that small companies are better, more precious, more deserving of government favor than big companies. By treating small business as special, they discredit the notion that government should be neutral.