The reason that companies like Logitech get cranky is that they assume the goods are probably grey market imports, which you're allowed to do, but you have to clearly advertise the fact that it has no U.S. warranty. But if you have receipts to prove that it was purchased in the U.S., they have no legal grounds to challenge you reselling it as new.
Last I checked, most (if not all) major retailers routinely take unopened returns and put them back on the shelves as new. So if the law considers those to not be new, then that is the most consistently ignored law in the history of the world. And I've dug through California's code, and I see nothing that defines "new" in any way other than "not used". And an unopened package clearly precludes use of the product, so at least in California, I'm about 99% sure that you're wrong. Obviously the answer may vary from state to state, but it seems unlikely that an unopened product could ever be considered anything but new by a reasonable person.
Again, as I said, for automobiles, the law is explicitly different. Once it is transferred to a non-dealer, it is considered used. But as far as I know, that is the only product for which this is the case, and only because there is a specific body of law that explicitly defines the transfer of an automobile to a consumer as "use".