He was "associated " with the line because he was supposed to have said it .This is based upon a phrase that Oppenheimer was "supposed" to have uttered upon seeing the Trinity Test Detonation. Oppenheimer was a student of Indian philosophy and religion and he often quoted stuff from the Baghavad Gita.
At the Trinity detonation he DID openly quoteanother Baghvad Gita phrase
that one stated.
"If the of a thousand suns were to burst at once into the sky it would be like the splendor of the mighty one"...
That line didnt play well with the press so, about 2 years later, Oppenheimer said that he was actually thinking of another line from the Bag.. that quoted Vishnu . This was your line>>>
"NOW I AM BECOME DEATH, THE DESTROYER OF WORLDS"" (Its actually funny because that mini quote is taken from a line in the Bag that is much more circular in its criticizing war.
Neverthelless, "The Destroyer of WOrlds" line played much better on tv and in the newspapers. DID HE ACTUALLY SAY IT At WHITE SANDS??? Noone really knows.
By the time he was supposed to have uttered the Vishnu line--Oppenheimer was at the beginning of his"COmmunist association" period and when he was being accused of pacifism and his "fellow traveller" accusations by the nascent Mcarthy era.