It is easier to prove a positive since it requires only the "smoking gun" to be made apparent. It is much harder to disprove a negative because it requires hypothetical smoking gun that could have caused the effect (Han's beating of Magnus) to be disproven. Since we don't have a record of every electromagnetic and sonic wave which passed through the room the day Hans beat Magnus, disproving the cheating claim is likely impossible.
It is easier to prove a positive since it requires only the "smoking gun" to be made apparent. It is much harder to disprove a negative because it requires hypothetical smoking gun that could have caused the effect (Han's beating of Magnus) to be disproven. Since we don't have a record of every electromagnetic and sonic wave which passed through the room the day Hans beat Magnus, disproving the cheating claim is likely impossible.