It's not at all just "because Stalin was 'evil' he'd start a nuclear war". It's like if Stalin died in 1930 and saying "Stalin was a rational man, he would never have started a "great purge" that would end with the death of millions including the old guard like Zinoviev, Kamenev, Bukharin." In the last years of his life, Stalin mounted a vicious campaign against Soviet jewry which revolved around the theme of "Zionist spies working for America and Israel, trying to destroy Soviet society". What was all that for then? Was it just because he was "old and bored" as the poster above said and that he had nothing else better to do than plan another Great Purge and mass deportations of Jews to Siberia?
I am of the opinion that Stalin planned a) another Great Purge to prepare his country for war with the West as he did before World War II and b) a Second Holocaust to eventually draw the West into war with the USSR. Communists of Stalin's breed were never known to shy away from the thought of nuclear war. Molotov, after Stalin's death said "The fact that atomic war may break out, isn't that class struggle? There is no alternative to class struggle" and I remember Mao said something like "If 60% of the world population dies but the end result would be a world without imperialism, then that would be a favorable thing".
Look at what Stalin did. He, for example, abandoned the very strong communists of Greece to right-wing dictatorship, because he wanted good relations with the west. He did not invade Yugoslavia. He wanted to reunite Germany, he toned down proletarian revolution for nationalism, etc.
One of the anti-revisionists (the Maoist crowd) main problem with Kruschev (sic) was his call for peacful co-existance, which they saw as betrayal of Stalins correct position on the matter. The truth, though, was that he only continued Stalins program.