Ok, so the entire cross-sectional explosion surface inverse square law calculation business essentially is meant to calculate the percentage of the explosion that hits you. So if you get that using those formulas increases the result beyond 100% of the explosions power, then something is wrong.
Like I noted on the explosion page, that can be because it isn't always as simple as using crossectional area, particularly then if the explosion is very close to the person in question. That's because the crossectional area is only a (very good) approximation the actual area that one would need to use.
What exactly the correct area is, is a bit hard to describe. Basically, if one sees the source of the explosion as a lamp and build a sphere around the person, with the source of the explosion in the center, then what we wish to do is to take the percentage of the explosion yield, that is equal to the percentage of the shadow of the person on the sphere to the spheres total surface.
So in certain very close scenarios calculating the durability from an explosion at close range just gets more complicated, but is technically possible. It probably would need some case-by-case fiddling, though.
In the case of hugging a small bomb the percentage of the explosion tanked would be close to 100%, although likely not quite 100% due to some little gaps remaining. Unless you're very close to the border of a tier, it likely makes no difference in tier at least.
I should also mention that in ancient times, before even I had any influence on such decisions, it was once decided that point-blank range explosions are usually ok to be assumed to scale in full, for better power scaling / simplification / fictional logic reasons or something. Basically like we assume characters scale even if attacks they tanked resulted in some minor environmental side effects because the difference between full power and what is tanked shouldn't be significant. (or more generally why we scale characters without much considerations of whether they tanked 100% of the energy beam or just 90%)
Nobody ever decided it changed, so I always assumed that was still the standard.

Even the explosion yield page technically only talks about non-point blank range explosions for the durability section. So yeah. Take that as you like.