Looked to me like he THREW the game!! That last bet was NOTHING like he usually does!! I think they didn’t want that creepy lefty gayish Ken Jennings to lose his title!
No, his ONLY possible way to win was to bet based on Emma having the wrong answer in Final Jeopardy.
IF James bet everything, he would still lose to Emma by $1 if her answer was also correct. Therefore, his only hope was if she had the wrong answer, he could beat her with a smaller wager and still beat the other guy.