Natural persons and corporate persons have different rights, though. And, until CU, corporations couldn’t put unlimited money into elections. Corporations, for example, can’t vote. They don’t have a natural lifespan.
Looking at the Bill of Rights, some of them make no sense when applied to corporations – what does the right to bear arms mean in the context of a corporation? Can a corporation join a militia? So, bringing in the Bill of Rights as if that’s some deciding factor seems wrong to me.
ETA: Back to the OP, since CU was decided, SCOTUS has become even more business friendly, so this is truly a waste of time.