With that usage, of course head-down position looks more subservient. A person who is fearful, or surrounded by a generally hostile population might perceive that as "more friendly" at a stretch of semantics, but that would say more about the culture and context.
My experience is quite the opposite. Heads-up with eye contact indicates an engaging personality, readiness to listen and see, and therefore a more sociable outlook. First thing you get taught in cadets or scouts or whatever is "heads-up!" - a ready/attentional posture.
Indeed, the widespread problem with smartphones is visible in any British high-street. People bimbling along, heads-down, necks craned, staring into the 6 inches of virtual reality through which they see the world. It's not only horrifying from the POV of their health and safety, it sends a "non-approachable" signal.