It’s just one of his supposed tools he can use in enforcing party line and loyalty among the elected. Good old fashioned leverage and blackmail.
The RNC chairman should have a committee assigned to fairly assess candidates so that we don’t get Democrat plants and nut jobs, like the shoe-in candidates that start saying stupid things near election day and are made the face of the party by the opposition.
There have been a lot of crappy nominees from both the “RINO Establishment” and “Tea Party Conservative” camps. Political skill is a factor that is independent of ideology.
None of those candidates so named lost because they were “too establishment” or “too conservative”.