Still mean, but yeah, I can understand it to some degree from the perspective that she was just, as you said, tired and grumpy.
I rewatched the scene. Littlefoot does indeed say “Go on! Go the wrong way! We never wanted you with us anyway!” But it was directed at Cera, not at Petrie. After Ducky says that Cera’s way is easier, Littlefoot doesn’t say anything else. He just storms off.
