I get the vibe that sensei letting Yamada off the hook there was less because he actually bought Ichikawa's argument and more because his teacher's instinct of "reward the quiet kid for actually talking" overrode his desire to catch/punish someone for a victimless crime.
He is literally telling his teacher that she is too retarded to realize that because she is forcing him to throw away candy she didn't understand that the teacher was asking whether anyone was taking candies to school. Nice.
How does "I haven't thrown away anything in the garbage bin" imply having anything throwable, particularly snacks, in the garbage bin?
Was he expecting "I don't use garbage bins" instead?
@CanisLupusArctos
The question: " Did you know something about the wrappers and bags from snacks in the garbage bin?"
Most people would deny the 'wrappers and bags from snacks' part since that's what actually matters