Apparently, he was too tired to race the second moto. That's according to his team manager, Larry Brooks, from this podcast interview with Steve Matthes. Brooks said James left it all on the track in moto one, and that after setting fast times in both practice sessions and running well and finishing third in the first moto, it was still a good day for the team.
As far as I can tell, James has not said a word to the moto media yet. I wonder when this silence will end? Actually, I wonder why it started in the first place?