I don't know the particulars of the installation, but I can think of one circumstance where I do not consider any bends in the flex, and most certiainly do disconnect the 'completed raceway' in order to pull wires: motors, and a lot of industrial equipment.
It's simply not practical to either pull from or feed into those little connection boxes on the sides of motors. If nothing else, they're nearly always located in an awkward position. So, the flex is disconnected, the wires pulled, then the wires and flex are fed back into the connection box.
I recognize that the language of the NEC does not provide for this situation .... but, having made serious attempts to 'comply,' there's really no alternative.
Is this always the case? No .... but we have to recognize the difference between a real bind, and a convenient bit of gamesmanship. Naturally, the "lawyers" will assert that there is no such thing ...
As for the C-body, or ANY conduit body, for that matter, I consider their utility as pulling points to be severely limited. The wire ALWAYS forms a loop, and getting the last half-inch of wire into the body is when the wire is almost insisting of damaging itself. The presence of the C-body might make the inspector happy, but that's it. Like the 'escape hatch' on a submarine, it's there to keep the ignorant happy.