That's not an accurate description of his views. He opposed the First World War on those grounds. He supported military action against Hitler. He believed the atom bomb was so terrible that any future major war would wipe out or seriously damage human civilization.
But that wasn't the point of my post. Russel was a world-class logician and philosopher. European scientists - the world's best - paid attention to him. His book severely criticising the Soviet system would have been known to them...so I find it unlikely that many of them would have had a useful idiots, naive, utopian view of Russia. Much more likely, they would have shared Russel's view of the tremendous danger of war in the atomic age and the need for international cooperation to prevent it. Other sources - for example Bohr's statements which I posted - corroborate this.
I could have used Einstein instead of Russell. His views were similar.