>>93106378Because the moment Aku realized Ashi wasn't under his control she TOAR open a portal in time and flung Jack into the past where his evil wasn't law. Depending on which time travel rules they're using, which clearly aren't trying to be realistic because Ashi didn't vanish instantly after Aku was killed, Aku techincally would've have been physically able to chase them to the past once they traveled through the portal because everything in the past has already happened so he would've just immediately faded away with the rest of the future.
