My friend thinks that if you sit in the shoulder press facing the machine and grab the handles with a neutral position (see attached image), the main muscle you’re targeting is the medial deltoid.
I argue that while the medial deltoid might contribute slightly more than compared to a normal shoulder press, the main muscle working is still the anterior deltoid regardless of whether you face the machine, or away from it, and regardless of whether your grip is pronated, supinated or neutral.