You have not proved a thing except that only individuals can be granted a patent. Now you wish to shift the argument to unconstitutional usage of the rights granted to a patent holder. If I hold a patent it is my property and I should I have the right to use it as I see fit and that includes selling the rights to a corporation. It seems you argument is about the wisdom of having and even encouraging corporations and not patents.
I will split hairs and say there is a difference between a government chartered corporation and and a cooperation in the sense of two or more individuals joining together for a common cause.
Government grants of incorporation are for the benefit of the government or a long time ago for the king. The would not be part of a free enterprise system which is ironic since most all of the ills blamed on free markets are blamed on corporations.
So I agree to ending government grants of incorporation but so long as they exist restricting individuals property rights in dealing with them.
Question: with this hypothetical patent that you hold, are you the inventor?
If you are not the inventor, then the Congress has no power to enact laws concerning [granting/enforcing] exclusive rights.**
This is the whole crux of my argument — the Constitution only grants the power to secure the exclusive rights to the creator*, and even then only for a limited time:
The Congress shall have Power […] To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries;
* — Creator
= author for copyright and inventor for patent.
** — This means that a patent is ONLY good for the inventor, not his company, not his estate
, not his next-of-kin, not some guy he sold it to
.