I don't quite see it that way, actually - there is no Constitutional prohibition against naming any organization as an enemy, especially one so overtly hostile so as the Wahhabis. And it is an organization of men that is being so named, not any system of religious belief. The Nazis had a very peculiar paganistic theology that was equally hostile, but it was not the religion that was the issue, it was the men with the guns, and it was not on the religion that war was waged, but on the ones using those guns to kill us.
That quibble aside, I am broadly in agreement with Mr. Warren on this issue. The Wahhabis are in a rather odd position with respect to their own state - they backed the House of Saud from the beginning, quite contrary to al-Wahhab's dicta that the doctors of Islam be the government. For that effort they became the beneficiaries of the regular charity that is one of the Five Pillars of Islam, only their benefactor was wealthy beyond anything in historical experience. With wealth came corruption, and lust for a secular power guaranteed them by doctrine but denied them by circumstance.
It would have been very difficult in the past to make this declaration given the traditional close relationship between the Saudi government and that of the United States, but now that the Wahhabis have decided to participate actively in destabilizing that country in an attempt to control the royal succession, all bets are off. They have flattered themselves that with money and covert military resources they can take on the largest State in the world; in fact, it may well turn out that they are incapable of utilizing it to subvert their own host state.
Certainly the recent public statements against terror by several prominent members of the ulema in Saudi Arabia were influenced by members of the royal family who are responding to the change in rules of engagement precipitated by the bombings in and about Riyadh. The question is whether those doctors of Islam are as much in control of "active measures" as they are of theological doctrine. If they are not then the declaration of the Wahhabi as formal state enemies is relatively useless; if they are, and if the Saudi royal family is really put to it, then "the bombing starts in five minutes."
I agree that the Wahabis are dangerous, but they are just part of the Islamic Jihad. If every last Wahabi cleric in the world answered his cell phone tomorrow morning and had his head blown off, the Wahabis would be out of business but the Palestinians, Iranians, Baathists and other Islamofascists would remain to be dealt with.
Where Wahhabism crosses the line is that the religious and political doctrine are inseperable. The political ideals are repugnant to our Constitution, and they should not be immune from government actions simply because they assert protection under the First Amendment. We do not give First Amendment protection to human sacrifice as a religious belief. Why should we be compelled to allow political beliefs that are declared enemies of our Constitution simply because they are also religious beliefs?