UPDATE: Yes, it would probably violate the Tennessee Constitution, too. And I don't see where the Governor would possess such power in an emergency anyway, in the absence of specific legislative authorization that, as far as I know, he doesn't have. Article I sec. 25 of the Tennessee Constitution provides: "That martial law, in the sense of the unrestricted power of military officers, or others, to dispose of the persons, liberties or property of the citizen, is inconsistent with the principles of free government, and is not confided to any department of the government of this state." Between that, and the rather strong Tennessee right to arms, it's hard to see how there could be any argument on behalf of an inherent power here. That said, a state anti-confiscation law is probably still a good idea, as plain statutory language tends to get more attention than constitutional argumentation in times of emergency.
UPDATE: Bob Krumm reports that Bredesen has reversed his position. And apparently there was such statutory authorization, sort of, though not for much longer if this anti-confiscation bill passes as expected.