Why Was The So-called Sacrificial Engineer Wearing Underwear?

So, why was the sacrificial engineer wearing outer space underwear, briefs or a loincloth under his cloak? The opening of PROMETHEUS is such a ritualistic scene, it seems to me that this should’ve been a moment for this extra-terrestrial humanoid (perhaps progenitor) to shed ALL. Instead, he’s wearing a pair of space “draws,” modestly covering whatever’s he’s packin’. Now, I’m glad we were all spared seein’ his “Jeremiah Johnson”…but the scene could’ve been shot modestly and tastefully…while implying nakedness. Of course this was better than having to sit through another “Dr. Manhattan” scene, but I think that the idea of nakedness would’ve been more in keeping with the spirit of the scene. Or…is this guy supposed to be “Adam,” being expelled from paradise, Eden…I doubt it. But hey, with all the wild religious speculation on this site lately…who knows? Ha! After all, the shame attached to nakedness in much of the world, is connected with the Judeo-Christian, Old Testament belief of original sin, Garden of Eden and so on. (Sarcastically) I thought Ridley and company were trying to dispense with the older beliefs. What do you folks think? ~N