That poll is ancient history. It was taken barely after Nehen got into the race. Nobody knew who he was.
I suggest you look up the bio of Eric Cantor. He was the house majority leader and got defeated in a primary a few years ago.
I helped Dave Brat take down Cantor. Brat is a far better candidate than Nehlen. He was an economics professor at a local college. And there was large spread dissatisfaction with Cantor in his District because he grew disconnected from his constituents. The Tea Party and a local organization helped take down Cantor.
Ryan goes home every weekend to his constituents. He won't lose in the primary. Better to defeat him in the general.
I know Cantors story and downfall well.