Calli: <whiteshark> Thanks for the link. they claim that Alekhine actually arranged it! Google translates the key paragraph as
"Alexander knew that his party had with Petrov is likely to end in a draw, and it will not leave him a chance to catch up with the third world champion. In the first rounds of champion got strong contenders: Stahlberg, Keres, Mikenas, he has not won a single party, already far behind the Capa. And rival Alekhine offered such an option: Petrov does not come out for the match, but France takes its second member. Such a development suited Latvians, if they were in the tail of the master or pervokategorniki, repeatedly played in representative tournaments, where the French have played lovers. The leader has taken Apsheniek that changed the course of the third on d5 in the French defense. The world champion's eyes flashed angrily, and even in the deep end yet won, but the match remained in Latvia 2,5:1,5."
In other words, Alekhine wanted an easier game in order to catch Capablanca and in exchange for Latvia not playing Petrov, France would not play Gromer who was their second board. Apparently Latvia thought this was a good deal because AA was champion and Latvian players could get favored status in future tournaments. AA was angry about Apsheniek going into the French exchange variation.