Oh DICE why did you forsake the mod community, can you imagine a frostbite 2 version of Day Z :O
I think this game was much easier to make using Arma 2's engine because, from what I can tell (not having played Arma, but have watched lots), it's removing more than it's actually adding. The inventory management systems look like they already exist within Arma 2, the map is the same from Arma 2, and it seems that most of the weapons are from Arma 2 or the add-ons.
This was made by one guy. He probably did whatever modelling or reskinning (zombies with blood on them) was required, recorded or sourced sound effects, set up the server-side stuff, and did a shittonne of tweaking to the code/scripting.
I don't think this would be possible with Frostbite 2.0 because there aren't really any existing games that use it in the same way that Arma 2 does with the BIS engine. He'd have to add inventory management, proximity-based voice chat, tweak stuff like draw distances, and so on with Frostbite 2.0 in order to make a comparative experience. It'd be nice to see, but I think this works as a great proof of concept, if anything.
I don't even want to think of how much it'd cost to purchase licensing required to use Frostbite 2.0...