Could Pasternak have saved Mandelstam from his arrest and exile which broke his physical and perhaps his mental health even prior to the extremes of poverty he and his wife suffered after his release and before his second arrest and subsequent death in 1938? Anna Akhmatova is ambivalent on this point but wonders about it in her essay on Mandelstam in MY HALF CENTURY, her selected prose, (Ardis Publishers, Ann Arbor, 1992).
"At the close of his letter to Stalin, Bukharin wrote: 'And Pasternak is worried as well.' Stalin stated that an order had been issued so that everything would be put right for Mandelstam. Stalin asked Pasternak why he hadn't exerted himself on Mandelstam's behalf, saying, 'If my friend were in trouble, I would do everything to help him.' Pasternak replied that if he hadn't done anything, Stalin would not have found out about the matter. 'But why didn't you turn to me or to the writers' organizations?' 'The writers' organizations haven't been involved in matters like this since 1927.' 'But isn't he your friend?' Pasternak hesitated and after a brief pause Stalin continued his queston, 'But he's a master, isn't he?' Pasternak answered, 'That's beside the point.' Pasternak thought that Stalin was testing whether he knew about the poems and that was his explanation for his shaky answers. 'Why are we spending all our time talking about Mandelstam? I've wanted to have a chat with you for a long time.' 'About what?' 'About life and death.' And Stalin hung up." (pp. 102-103)
She goes on to say (footnoted p. 375) that "Everything about this phone call requires the utmost scrutiny." Akhmatova also notes that Zina, Pasternak's wife, "hated the Mandelstams with a passion and thought they had compromised her 'loyal husband.' "
Well, who knows what one would do in a situation when you could be imprisoned, tortured, killed. Pasternak may well have been trying to save his own skin, in addition to aggrandizing himself and insinuating himself further into Stalin's good graces. It happens all the time, this cowardice, dissembling, back-scratching, brown-nosing among writers and poets, reference the recent controversies surrounding the actions of the young Milan Kundera. Or the egregious example of Gunter Grass in his Waffen SS days.
Or the refusal of poets in London to help organzise, provide a venue for, or even, out of fear, attend any readings in support of Salman Rushdie after the fatwa was issued.