It just seems like there may be something wrong. It looks like the joists are 2x4's on the flat, unless they are floor trusses. But even then, to me it looks like some of the angle irons are only fastened to one 2x and nothing but drywall anywhere else. Maybe There is something else I am not seeing.
Those two photos facing the door are deceptive, but those “on the flat” 2x4s are in a dropped ceiling not where the hangar brackets are located. Check out the right side of the first photo to see that.What is that flat black membrane above the 2x4s laying flat? I am sick like you are that they could be the bottom stringers from trusses but if that's the case I'm not sure what the black is.