Almost all of that is spot on.
Especially the boy talking as the cliffhanger, then completely reshooting the scene for this episode. Absolutely terrible.
My guess as to why that is done... JUDITH.
In the comics Judith dies with Lori, so is not apart of this scene. As soon as they go outside the boy panics and wants to turn back. He starts saying mommy just like in the cliffhanger. Thats shot for shot how it happens.
The difference with the show, is they can't do a fight scene with Judith there cause she would start crying or be hurt. So they have to now add an extra scene to dismiss her character. So instead of it jumping off immmediately like its supposed to, that entire ridiculously out of place scene with them all standing still near a bush talking in a crowd full of zombies where Gabriel takes the baby is basically just there to write Judith out of the episode so they can get to the action.
Ideally it goes from them stepping off the porch right into him saying 'mommy' right into the jumpoff... which is what happens originally. All the extra lets stand near a bush and talk is there to try and wrap up tv plotholes.