When did I say he didn't.
Well he switched with Shin's weapon and not shin himself.
it doesn't matter if it's living or not. Sasuke switched places with Naruto at one point during the Kaguya fight to get into position for sealing at one point before she teleported them to the ice dimension I believe so yeah I think he can switch places with living objects.
OT: if Kakashi could have his Susanoo use Kamui to have Kaguya's ash bones phase through them both, then there is no reason why Sasuke, a Rikudo/Rinnegan/EMS user couldn't use Ameno while Susanoo is active.
On another note: this swapping his sword into someone's head is not something I think Sasuke can do easily in theory. Maybe the smaller the object the harder it is to get an accurate swap perhaps. Or maybe he just doesn't do it because it would be lame to see.
Think about it, you wait all this time to see an epic battle only to have an opponent get done in by one attack and a battle...THE BATTLE...ends in one page. That would be very lame.