Kasner was a useful idiot for Eichman who was hopping that if he appeared to try to help save some jews he might not get executed after the war (The allies promised this)
Kasner in his defense with paying ranson was no differnet that the “Blood for trucks” idea in some charedi circles. The Nazis were not interested in saving jews, they only wanted the money from American jews. The Nazis generally were not bribeable, jews paid them the bribes and the Nazis killed them anyway.