A lot of those molecules are bound up in cells, they are not freely diffusing in blood. Even those diffusing in blood are not uniformly distributed, blood is highly dishomogeneous.
Routine metabolic paneling and serology does test for molecules that are uniformly distributed in blood. I can't say it any plainer than that. Of course many possible testing targets are inside cells, but these tests were not claiming to look at any intracellular targets, at least as far as I know.
They weren't really clear about what tests they could perform with their technology, but they did say they planned on offering the "full range" of blood tests.