In my case, I really don't track who is who in the spin offs, all the spin offs are already anonymous to me to a large part. Therefore, sending songs anonymously and scoring them will not be a breakthrough on my part.
I remember last edition, people wanted the John spin-off so we could send whatever we want without bothering about the votes. I think this is a good chance to be our very true selves and send anonymously what represents us most, without caring if people will like or hate it.
About the conspiracy regarding people not keeping the secret,
First, rigging is possible in every contest, be it the scoring game or the prediction game. I (want to) assume that most of us are grownups with conscience.
Spin-offs are more laidback and for fun idk if anyone is that ambitious to rig it for the sake of winning a spin off.
Plus, outing yourself to someone is eventually going to hurt your chances, so I doubt anyone will do it unless they is dumb lol