I haven't read Liberal Fascism, so I won't opine on the book overall. But Jonah Goldberg's contention that big companies in the early 20th century welcomed antitrust and other regulation to promote their own interests is only part of the story. There was also tremendous resistance to regulation, hence such court battles as Standard Oil v United States. Many business titans of the day equated largeness with efficiency, and thought competition wasteful. They did not encourage the federal government to break up their companies.
Progressivism also got some business support because the alternative seemed to be someone like William Jennings Bryan. The ambivalent relationship between government and business was exemplified by that between Theodore Roosevelt and J.P. Morgan. Morgan supported Roosevelt's reelection because he knew Roosevelt would win, not because he was happy the president had launched an antitrust suit against Morgan's Northern Trust. And when the two men cooperated, as in the Panic of 1907, which I recently wrote about, it was because they felt they had to, despite their differences.
UPDATE 1/12: More thoughts above.