Naivete is childish. Jesus was expecting His disciples to grow up in their understanding of the chasm between good and evil,
I am sure they did not have the same opinion of the ScribesPhariseesAndHypocrites as Jesus because their spiritual eyes were not open. They saw through eyes of flesh which told them that those ScribesPhariseesAndHypocrites were the wealthy, elite, prominent, powerful people in their society.
They did not see them as the poison they were.