Ultimately I suspect if they wanted to make these in significant volume, die casting or loss wax casting then machining would be correct route forward. 3D printing metal is expensive and the parts are likely to not be as strong. Most 3D printing (sintering) processes for metal result in a slightly porous part that needs sealing, those small gaps produce imperfections.

https://en.m.wikipedia.org/wiki/Die_casting

https://en.m.wikipedia.org/wiki/Lost-wax_casting

Take a look at turbine blades in jet engines, they are incredibly complex with tiny air holes. They are made using a loss wax then machining process.