Yep I think safes can safely (little pun there) be categorized as Accessories. I don't have that model. The one I gave my daughter for her pistol is the one the NRA sells online or in person, depending on where you live.
Keep in mind, (if you don't already know this of course) that there are a couple airlines that will not let you travel with a pistol under any circumstances at all, and they even balk at LEO's traveling with their side arms, but they don't actually have a choice and then those are checked through as luggage Not carry on................. Usually. The rest of the Airlines will insist, well ok the TSA, that the pistol be unloaded, no ammo at all anywhere, checked or carry on. And possible the Magazine in a separate place. Whether that can go as carry one I'm not sure I forgot to ask, but I would not bet on it. The Mags may not have to be in a safe just in your checked baggage, but the pistol has to be in that safe, and they will check to make sure all the t's are crossed, and the i's dotted, and that it will be in a hard sided piece of luggage also.
Also make sure of your route before you start on a road trip. There are more than one State that restrict, where and how or even if you can transport a weapon through their state. Yes despite the fact that most every state has a reciprocal agreement with other states to accept their CCW's Permits. Weird yes I know.