Fourth seat fiasco

I got a press release from Sen. Orrin Hatch’s office today, announcing that he, Sen. Joseph Lieberman (I-Ct.) and Delegate Eleanor Holmes Norton (D-D.C.), have reintroduced the D.C. House Voting Rights Act.
This is the bill, otherwise known as the grand compromise, that would give Utah a fourth seat in the House in exchange for giving the District of Columbia a seat. The District’s seat would likely go to a Democrat, and Utah’s would go to a Republican.
And everything would be fine — except the Constitution.
“The House of Representatives shall be composed of members chosen every second year by the people of the several states,” it says, in Article I, Section 2.
News flash: D.C. isn’t a state.
Hatch says, “I have studied the constitutional and policy issues in depth and am convinced now as much as ever that the Constitution allows Congress to provide a House seat for the District.”
I don’t get it. But in any event, this grand compromise would end up being challenged in court, and that could drag on. Utah is bound to get a fourth member after the 2010 Census anyway, and that seat wouldn’t be diluted by the addition of two new seats to the House.
Yes, the District deserves representation, but only if the Constitution is amended. Am I missing something?