That's literally just doing sub-assemblies. There was probably a way to do it without having to cut the hand off and just leave it and the gun attached to the body instead, but that's how you have to handle more complicated stuff sometimes. Either simply for the sake of building it, or just making it easier to paint shit. The old "if you can't get a brush to that spot you can't see it" is bullshit when it's something like a railing blocking access that you can clearly see around, or a shield blocking access to something visible from an angle you can't paint from.