Yeah you missed the point of the winter season man if you are asking this question. Like many have said here the point of the winter section and playing as Ellie is to show her progression from a scared, innocent child to a girl who is becoming hardened by the world and has clearly learned how to take care of herself by observing Joel. Obviously during the year they were together Joel trained her on how to use weapons and how to kill if she needed to.
The whole David scene with her chopping him to kibble just shows her frame of mind in that moment. She was sickened by David and wanted him to go away by any means necessary. I think she just lost all control of herself and hacked away at him fevereshly. The whole point of Joel finding her and consoling her shows the progression of their relationship and shows that even though Ellie has grown up a bit and can kill if she needs to Joel still feels the need to console her and be there as a protector.
I also feel like Joel does not want Ellie to become like him which is why he grabs her and tells her to stop, he knows if you kill enough it can change who you are which Joel does not want. He wants her to remain an innocent little girl who relies on him to do the dirty work so she doesnt need to. But Joel knows deep down that is not possible in this world. The whole point of the Winter section was to show Ellie's progression from innocent little girl to someone who will kill at a whim to survive. Its a powerful section of the game.
1) Joel did not have an idea what happened to Ellie, she was in danger.
2) Even after Joel learned about that from the two cannibals, he still feared for Ellie, since he didn't know was she okay... probably was even more scared for her because the cannibal said "she's David's new pet".
3) David was standing, Ellie was crawling. The area you can see is much different in those positions.
4) Ellie didn't stab him "to make his body flip over", he slashed him to the arm with the machete.
Out of curiousity, why to troll, OP?
I have acquired the grade of Master in The Last of Us story/character/game knowledge as I have played it through 9 times.
... I have no life.
as others have said, though when he says "baby girl", he says it for the second time. The first was when he was holding his dying daughter in the prologue, so it's kind of solidifies the father-daughter role