Why is the Bush administration defending the FACE Act?

The Freedom of Access to Clinic Entrances Act turns a local crime (interfering in any way with the operation of an abortion clinic) into a federal case. The justification for the law hinges on the modern fashionable-but-absurd notion that any thing that can be tied to something else in another state (and in which money plays any role, large or small) brings that thing under the jurisdiction of the federal government, courtesy of the Constitution's "commerce clause", should the government choose to exercise such jurisdiction.

In a case before the 5th U.S. Circuit Court of Appeals, the argument is being made that a man's act of violence against a Houston abortion clinic (ramming his van into the building) may dissuade abortionists in some other state from practicing their craft, and thus this is a matter of interstate commerce, and thus the malefactor can be prosecuted in federal courts under FACE. The Bush administration has gone so far as to dispatch an Assistant U.S. Attorney General to bolster this argument.

I'm not jumping on this simply because it involves abortion -- FACE is bad law because it relies on a twisting of the Constitution that leaves nothing of significance outside of Congress' grasp.

I realize that the Bush administration has a less than ideal record on defending the Constitution, but I wish it would draw the line somewhere. This case would be a meaningful place to do so.