Serving in a classified government job and serving in a high-profile APPOINTED position are two very different things.
In the former, one cannot be discriminated against. In the latter, one can.
In the former, one has little chance to influence policy. In the latter, one wields great influence upon policy.
In the former, it is one voice among thousands and, therefore, basically silent. In the latter, it is one (or four in this case) among a few, resulting in a very visible and effective soapbox upon which one can speak much, much louder.
Big, big difference indeed.
Name one gay person that Bush has named to "high level" position within his administration. Cabinet officers dont even have much power in Washington, why are you so freaked out by people five or six layers down in the organization?