Right now it's more of a question of "how" not "if." We would need to adjust the degree of which the game lets you control Nana when she's desynced before we even begin to discuss the if part.
But let's say we can't figure it out, then I suppose the next question is what to do with their throws. There are options to getting rid of the alt grabs, like just removing Nana's grab from the game, and maybe something like "neither Ice Climber can input a grab within 'X' frames of another Ice Climber throwing an opponent" but I'm no coder so don't ask me if that's even possible to code.
There are big reasons why we have left the IC's alone... they are *****es to work with
I don't know about you, but I don't want him to be yelling "PK FREEEEEEEEEEEEEZE" over and over again throughout the match
And as Shadic said, the PK Freeze voice effect from his original Neutral B doesn't really fit the move either.