But they did risk randomization. After all, Diva voted for Bigby Wolf. Now, perhaps this was no danger to them, as perhaps Bigby Wolf is also not in the staff.

But! This is not a plan they could have contrived easily beforehand, for the very reason that they could not have predicted no person in the trial wouldn't develop a grudge against one of their own, as Diva developed a grudge against Bigby. If they can't communicate during the trial, the safest plan would be for two to coordinate and both vote for the same person in the event of a vote to abstain. But they didn't do this. And there was no indication anyone was secretly communicating during the trial.