From Wikipedia:
The Supreme Court of Israel overturned most of the judgment against Kasztner in 1958. The judges overturned the first count by 3–2 and the second count by 5–0. The longest majority decision was written by Judge Shimon Agranat, who said:
During that period Kasztner was motivated by the sole motive of saving Hungary’s Jews as a whole, that is, the largest possible number under the circumstances of time and place as he estimated could be saved.
This motive fitted the moral duty of rescue to which he was subordinated as a leader of the Relief and Rescue Committee in Budapest.
Influenced by this motive he adopted the method of financial or economic negotiation with the Nazis.
Kasztner’s behavior stands the test of plausibility and reasonableness.
His behavior during his visit to Cluj (on May 3) and afterwards, both its active aspect (the plan of the “prominents”) and its passive aspect (withholding the “Auschwitz news” and lack of encouragement for acts of resistance and escape on a large scale)—is in line with his loyalty to the method which he considered, at all important times, to be the only chance of rescue.
Therefore, one cannot find a moral fault in his behavior, one cannot discover a causal connection between it and the easing of the concentration and deportation, one cannot see it as becoming a collaboration with the Nazis.[41]