That cap is what a person can give to a campaign.
CU let companies donate to campaigns and PACs. This talk about state by state changes to put a stop to that is nice (Montana, Hawaii). But Elon Musk is not a company, he actually is a person.
You can give unlimited to a super PAC. Ok, next you get rid of super PACs, which came after CU, fine.
But now still, how does that stop an Elon Musk going out and spending $100m on political advertising as a private individual? That’s what the Musks of this world can still do after you get rid of super PACs.