I mean they're probably gonna charge extra for him, so hopefully they make it worth it.
You know, while I think Space Marines are a better fit thematically for small squad vs a Horde, this probably has a lot more options for characters with out absurdly skewing the power levels.
Of the top of my head I could see various forms of cogboys, at least a couple specialized Guards(at least Catachan and Krieg), Interrogators of various Ordos(especially Xenos for some Tau/Eldari weapons), Crusader, Squat, Commissar, a Sister Repentia. Depending on how much they go for Rule of Cool versus sticking to the fluff, a Kroot, Neophyte/Scout Marine, and some Assassin's could work while straining believability.