Why name it after a Nazi?
Von Braun was no ordinary German scientist, trying his best to fight the good fight while under the Nazi regime - he was an active participant in it.
He willingly became a member of the Nazi party in 1937; he was an honourary member of the SS; he used concentration camp slave workers at his Mittelwerk rocket production plant where 20k people died.
They should have named the probe Sergei Korolev instead.