Evicting someone from wraiths is a terrible idea. Only one of us is the real wraith. That player can do nothing, as the two spies will cause the moves to be bad for wraiths every round. If we evict anyone and end up being wrong, the real wraith can now influence the play and have wraiths do things. Onion may even allow DoubleCap's "agree to everything" clause apply to evicting the final spy, meaning wraiths would have free reign.
So, wraiths evicting anyone is terrible and will only happen if the other spy (Kuro) is dumb.