I'm not sure what a HMMWV A2 tie-down looks like, but it probably does not swivel. And, if it does, it is probably more like the tie-down in an M105A3 trailer, or the M1101/M1102 trailers. Those are different than the style that are welded to the bed sides.
I seriously doubt those little tabs or their swivel base will handle 2300 lbs. That would mean you could put a 7000+ pound truck in the bed of a 5-ton and lift the bed off the truck with just 4 of those tie-downs. I doubt it.
Since 4 of them can obviously support the weight of a 5-ton bed in a static lift, I would say you can assume they will hold at least 500 lbs.
Of course, the type of loading will affect their reliability. I'm sure whatever rating they carry is specified for a specific load direction and it decreases as you move away from that.
In any case, when you are tying something down in the bed to *multiple* points, I think it would have to be darn heavy to cause a failure of one of these, unless it was really done improperly.