if i remember correctly, the mercora simply state that the "nesk had redirected the comet to hit that settlement" assuming that the nesk could only do this by strategically placed explosions, then wouldn't the animorphs see (or hear) some kind of explosions? why i am saying this is because perhaps the nesk calculated and measured that the comet was going to hit that settlement and they figured that the best thing to do is to leave. if this is true, if tobias and ax carried any guilt they shoulda have to worry. haha