I am not a historian of course, but by that time I don't think serious politicians had illusions about the upcoming war between Russian and Germany.
Russia was not in alliance with Germany. The Non-Aggression pact with Russia was similar to the pacts Germany had with other countries. For example, Germany had a Non-Agression pact with Poland, and Poland took pieces from Czechoslovakia when Hitler took Sudetenland in 1938. This didn't prevent Hitler from attacking Poland.
The Soviet-German pact was just buying time in preparation to the future war.
The Soviet Union had been seeking to create a collective security military alliance with France and Britan against Germany, because it considered the war with Germany inevitable. But after the negotiations failed, Soviets made the pact with Germany. https://en.wikipedia.org/wiki/Molotov%E2%80%93Ribbentrop_Pac...
We should remember, this Orwell's text is a newspaper article, so may be a propaganda to a degree. For example, Orwell himself multiple times called his work for BBC a propaganda - see his resignation letter to BBC and the famous quote from his diary:
> Our radio strategy is even more hopeless than our military strategy. Nevertheless one rapidly becomes propaganda-minded and develops a cunning one did not previously have. Eg. I am regularly alleging in my newsletters that the Japanese are plotting to attack Russia. I don’t believe this to be so, but the calculation is: ...
https://orwelldiaries.wordpress.com/2012/03/14/14-3-42/
In this article what is interesting to me is how he explains that Hitler poses as a Christ or Prometheus, a self-sacrificing heroic victim. (Because I am not familiar with Mein Kampf and Hitler's rhetoric in general).
The rest - not a revelation. BTW, he attributes the "Better an end with horror than a horror without end" to Hitler, but that's wrong, the phrase has a different author.