The Actual FCC Net Neutrality Repeal Document. TLDR: Read Pages 82-87 [pdf]

Here are some links to the relevant antitrust laws:

Sherman Antitrust Act (1890) https://en.wikipedia.org/wiki/Sherman_Antitrust_Act

Aspen Skiing Co. v. Aspen Highlands Skiing Corp. (1985) https://en.wikipedia.org/wiki/Aspen_Skiing_Co._v._Aspen_High....

Transparency in network management and paid prioritization practices and agreements will be relevant.

"We find that antitrust law, in combination with the transparency rule we adopt, is particularly well-suited to addressing any potential or actual anticompetitive harms that may arise from paid prioritization arrangements." (p.147)

If antitrust law is sufficient, as you've found, there would be no need for Title II Common Carrier regulation in any industry.

We can call phone numbers provided by any company at the same rate because phone companies are regulated as Title II Common Carriers. ISPs are also common carriers.

"Public airlines, railroads, bus lines, taxicab companies, phone companies, internet service providers,[3] cruise ships, motor carriers (i.e., canal operating companies, trucking companies), and other freight companies generally operate as common carriers."

https://en.wikipedia.org/wiki/Common_carrier