To All Ubuntu / *nix guru outhere,

I read the 2unix script and I still don't understand why it's removing the  "Windows partition data".
I'm pretty sure the thumbdrive is mounted under m1 alias, but why do we need to zero the sda partition. That doesn't make sense to me. (Is it a preparation in case I need to copy the mounted m1 to sda?)

My aim is to dual boot Windows 10 with it.