It was to show his chakra growth.. Besides he wouldn't need a defense against shin if Naruto would've left like Sasuke told him to, then he would need to protect his child.
I guess you have no counter for his clones or humanoid susanoo? Lol
Left when he told him to? I haven't read the manga in a while and my memory on that moment is fuzzy to say the least but from what I do remember didn't Naruto leave the situation to Sasuke? so really it's his own fault that in the time Badly launched an attack towards his daughter that all he could think of in that space of time is to simply move himself towards her and use his own body as a shield...the Uchiha famed clan and his choice of defense is that.
No counter for his clones or humonoid Suanao? No idea to what you're referring to or what moment they were used so you'll need to be more clear because I have no memory since Gaiden of him using clones though he used that head of his susanao for no reason though