It certainly looks legit... It's a weird frankenstein of Halo and CoD parts. The legs and upper arms are CoD sculpts, but the chest, lower arms, and waist are Halo parts. Historically parts from the two grounds aren't all that compatible, but maybe they did some mods on the tooling to make it work better.
Not crazy about the stumpy chest and forearms from Halo, as they look small to me after years of customizing the CoD parts, but I guess once you get them all in a group, those little nitpicks will fade away.
It at least looks like they spent some money to tool some accessory gear. Here's to hoping they print his eyes properly in production so he doesn't resemble Droopy Dog on my shelf