Because of the heavy censorship.
Back in 1942 the US Office of War Information instructed MGM to give up plans to make the film. Both British and American war offices agreed that triumphalist films about the British empire did not suit the war effort, which was supposed to be about liberal democracies united against brutal fascism.
This film also portrayed the Russians as enemies. Portraying them in a negative light probably worked well in 1950, during the early days of the "Red Scare" and start of the Cold War. But during WWII, both the U.S. and Britain were allied with Russia in fighting the Nazis, so I can see why the 'Powers That Be' told Hollywood to quash this film for the duration.
Even after the war, they delayed production because the imperialist themes portrayed wouldn't play well with the Indian govt. But after independence in 1947, it became more acceptable, so they went ahead.
The difference between stupidity and genius is that genius has its limits. -- A. Einstein