The biography's author, Zev Chafets, contends that Limbaugh got snubbed because he taunted Bill O'Reilly in the book. But media critic Michael Wolff says a much "greater clash of Titans" explains the freeze out: Roger Ailes, the chairman of Fox News, despises Limbaugh. Wolff explains:
In some sense, they are the same person: broadcast hacks with a taste for trouble-making and politics, both with substantial intelligences colored by grandiosity and militant hostilities. Together they have forged the modern conservative sensibility—bellicose, loquacious, conspiratorial—as well as their own individual conservative-themed media empires...
Ailes, who has been talking about writing his own book for years—with no progress—is genuinely miffed that Limbaugh has gotten himself a book (conservatives, curiously, believe in books—they’re great advertisements as well as money makers). Limbaugh’s vast publicity—his extroverted expressiveness—rankles Ailes. The idea that Limbaugh might end up as the grand and historic conservative of the time—pretty much the only one who is not on Ailes' payroll—is extremely depressing to Ailes.
That Limbaugh seems to have overcome his personal difficulties—his deafness, his drug addiction, and, not least of all, his weight problems—and become ever more public, hurts. Ailes, on the other hand, is more and more phobic about being in public, ever more self-conscious about his weight, and increasingly obsessed with his own personal safety (the Arabs are after him).
Still, this is exactly what keeps these guys going: rancor, ego, paranoia, and the chess moves of self-promotion.