It turns it into a souped-up rubber ducky, with networking and serial capability. What I really want to allow it to do is bridge usb networking and wifi to create an out of band network to run network attacks from another device (like my phone)
I guess what I should check next is how to get Sailfish OS to act as a rubber ducky as well, so that it makes only one device to plug in for both the out-of-band network and the commands to compel the computer to use the network.
I fixed the RNDIS default config on Sailfish OS and got most of what I wanted outside of this. It's still a really cool project and I really hope at some point we'll manage to get it to do what I wanted it to do.
But now if I connect my Sailfish phone directly to a computer it will create an out-of-band network between it and the computer, enabling me to have the computer communicate with, oh, say, the software running in a LXC container on the phone.