Autonomy and Hedonism

Shafer-Landau considers a number of arguments against hedonism (the view that happiness or pleasure is the only intrinsic good) in the second chapter of the book I'm using for my introductory ethics class. Here's one of these arguments:

The Importance of Autonomy Argument

(1) If hedonism is true, then autonomy contributes to a good life only insofar as it makes us happy.

(2) Autonomy sometimes directly contributes to a good life, even when it fails to make us happy. 

(3) Therefore, hedonism is false.

The argument is clearly valid, but are the premises true.  I'm mainly concerned with (2) (since (1), as Shafer-Landau suggests, is difficult to deny).  Do you think that autonomy contributes to a good life--that is, it makes one's life go better--even when it fails to make that person happy?  Why might someone reject this claim?