The degree of bending is not necessarily surprising; a 1.8-inch sag in the ceiling would result in an 8-in deformation, assuming a circular profile and 8-ft studs.
I'm looking at this photo while eating my #12 McDonalds meal and noticing that the studs look like french fries. Probably have the same compressive strength as a french fry.
The floor is being held up by the pairs of studs that crippled towards each other. An interesting structure, actually. The other studs are window dressing but those curved with mid-span bracing are really quite strong.