Maybe because they are aware that Nu is already paying for an Android wallet that is capable of using shapeshift.io? 
No seriously, the Android wallet will be great (I hope) for exchanging back and forth between NBT and other crypto currencies that are supported by shapeshift.io
But exchanging BTC to PPC would need to be changed from BTC to NBT and from NBT to PPC with that wallet.
I can’t say that this is bad for Nu, though 