That whole section of code pertains to primary elections, and the process by which a party chooses its nominee.
If the GOP tries to annoint a person, and McDaniel opposes that candidate, then the party has to conduct an election to make the choice, and in order to properly be on the general election ballot (eligible for office), the nominee has to either be unopposed (in the primary) or receive a majority of votes in the primary/runoff.
Cochran conceding does not make McDaniel receive a majority of votes in the primary.
The first part has to do with a vacancy after the primary is settled. It's not settled yet, so it doesn't apply yet.
-PJ