Ok yes "exponentially" was hyperbolic. Mass scales linearly with volume, but volume is proportional to the cube of the radius (not linear).
Also, in practice, small imperfections can have a disproportionate impact on the resistance of the sphere so design codes typically apply conservative reductions that can have a big impact on actual thickness requirements.
I read the report when it come out. From memory, no. It never had any components or certification for human pressure vessels. IIRC theres no existing regs for carbon fiber and it would have cost like $50M to do the design and test work. They did buy some things, like the viewport, from companies who do certified parts, but instead opted for the same design minus any test certs to save money. The craft was never certified or inspected by the uscg. It did have a registration for a while, but they had to play find-a-new-district-sign-off shell games for a while, then… just stopped bothering.
Also, in practice, small imperfections can have a disproportionate impact on the resistance of the sphere so design codes typically apply conservative reductions that can have a big impact on actual thickness requirements.