Recently I had occassion to take a brief look at the 1941 Chess Reveiw Annual (published NY, NY by I. A. Horowitz). The match tournament in the USSR was reported on, (I forget which month) but there was no mention of the tournament being to challenge Alekhine for a world championship match.
All things considerd, I would suggest that there was no formal arangement or, in fact, any type of agreement for a WChM and as far as the rest of the world was concerned - the 1941 USSR tournament was to decide the best player in the Soviet Union.
Since in the Soviet system all capital belonged to the State, to mount a bid for a WChM would need to be financed by the Government. Within the Soviet system, all the players and tournament organizers associated with the match, could have understood that whoever won the tournament would be backed by the State in a bid for the WCh title.
Thus the Soviet literature would consider this a bid for a WChM while the rest of the world, including perhaps Alekhine, saw it as a match tournament to decide the best Soviet player.