The likely answer: poor people. Spending on social programs to help the poor will get slammed down by the spending freeze (Medicaid, however, is exempt from the freeze). Ezra Klein outlines that the discretionary spending programs without huge lobbies and constituencies will be smacked by the freeze.
For example, agriculture subsidies should be cut. But do we really believe that heavily lobbied, politically charged ag subsidies will be frozen or cut by self-proclaimed "fiscal conservatives" like Ben Nelson, Chuck Grassley and Blanche Lincoln -- all of whom come from predominantly agricultural states? No way. Since there isn't a group of powerful, wealthy lobbyists known as Big Poverty, there's not enough power to guard social programs from the freeze.
So far, I've been ambivalent about the spending freeze since we haven't heard all of the details. But some realities in Washington are perpetual. "Fiscal conservatives" are only "fiscally conservative" about the spending and the earmarks that don't belong to them or the special interests that feed them.