To sum up: China’s current rulers do not seek preponderance solely because they are the leaders of a rising great power or simply because they are Chinese. Their desire for dominance and control is in large measure a by-product of the type of political system over which they preside. A liberal democratic China would certainly seek a leading role in its region, and perhaps an effective veto over developments that it saw as inimical to its interests. But it would also be less fearful of internal instability, less threatened by the presence of strong democratic neighbors, and less prone to seek validation at home through the domination and subordination of others.While I think it's true that a democratic China would be less concerned about the presence of democracies on its borders, the other two factors don't ring true. It's not clear why a democratic China would suddenly become less fearful of internal instability. Don't all countries fear internal instability? A democratic China may provide more productive avenues for domestic grievances to be aired, but it's not as if the end of single party rule would make subsequent regimes comfortable with massive internal instability (see: India). Second, the idea that a liberal democratic China would be "less prone to seek validation at home through the domination and subordination of others" is belied by, among other thing, America's post Cold War foreign policy record.
The real question Friedburg is dancing around (and may address later in the book) is whether a democratic China would be a more pliant one with respect to U.S. hegemony in Asia. There is every reason to believe this will not be the case. The demands of national pride and strategic common sense would seem to dictate that a more powerful China will take a more forward-leaning role in policing the sea lanes it depends on for trade and natural resources.
Update: Larison adds another comparison:
The record of late 19th-century Britain or Meiji-era Japan ought to disabuse everyone of the notion that having a liberalizing and democratizing political system precludes the pursuit of an aggressive foreign policy. Rather than looking at America’s post-Cold War policies around the world, a more useful comparison might be with America’s early republican history as an expansionist power in North America. Early republican America was the most liberal and democratic country in the world by the start of the nineteenth century, but that hardly prevented it from using force or dominating other peoples. Increasingly democratic politics included expansionist goals that shaped U.S. relations with the rest of the continent. A democratizing China might or might not become more aggressive toward its neighbors than the current regime, but the assumption that a democratic China would be less aggressive in its dealings with other states in the region is a shaky one.
Just so. The makeup of China's government is not immaterial to these questions, but we shouldn't simply assume that a democratic China is going to relinquish longstanding territorial claims or strategic interests because it's a democracy.