Recall Trump had 16 adversaries.
First stroke of Trump's genius was to insist on an odd number of candidates.
That is the leader (No. 1) gets to be front and center
Trump demolished the opposition...Low energy Jebb ....little Rubio.....Lying Ted....
Most difficult was to remove Carson,,,Pediatric Sugeon...squeaky clean......so Trump focused on his lifestyle.
However.....Trump subsequently gave a Cabinet position to Carson in his administration.
I would suspect that Trump already decided that he wanted Carson in his Cabinet.