Yes, it would be bad. He could see all the permutations of time, as well as attempts by other Shards like himself to do this very thing. By directly intervening on such a granular level, he risked creating a society where no one learned, and where civilization did not progress. By supernaturally forbidding warlords, he would also stifle scientists and artists. By removing the capacity for violence, he would also remove the capacity for mercy.
