Physics C Mechanics but not Electricity and Magnetism

Colleges will likely not know that the HS stopped offering a course. Or care.

Here is the reality. While your son will spend countless hours on his application, AOs will spend 10-15 minutes reading it. They will not have the time or the inclination to review the transcript course by course. And they certainly will not xref against the course catalog.

Whether he should forgo the course is a different question and depends on his future plans and what he proposes to take instead.