Only natural persons may participate in the political process.
Section 1's opening clause,
“The people of the United States
will ordain and establish United States government under this Constitution,”
“A citizen may conduct such self-governance
and an inhabitant may donate labor,”
together prohibit foreign governments and corporations from participation, because citizens and inhabitants must both be natural persons in the law.
Amendment XXVIII, (proposed), Section 2:
"No private person or entity
will conduct granting, apportionment, districting,
or the holding, tallying, monitoring, or auditing of elections.”
What the amendment prohibits altogether is private control of public electoral functions. Candidates, parties and private individuals and entities sacrifice control over how much speech will be offered for the public's use, and who will be able to provide it (see Nonpartisan Granting and No Contributions Needed). And this keeps foreign governments from involving themselves in our governance, something the Constitution already at least implies (see Foreign Governments and Campaigns). Control is not a need but a want. Wants are not protected as no right is burdened (see Public Debate is Self-Governance).
Nothing in the Constitution allows private control of public electoral functions. Privatization of public political functions is simply too dangerous. Granting governance power to corporations or privately-owned organizations, however well-intentioned, makes it privately transferrable: ownership such as shares can be sold or inherited. Privatization means foreign governments can purchase power over our government functions. It also removes accountability to the people, who can't break the contract or impeach or refuse to reelect corporate officers.
Section 2 works with this section by prohibiting the government’s delegating the granting function to parties or other private organizations, corporations, or individuals (see Accountability and the Public Elections Clause and Impartial Granting for more information).