Everyone in the world should basically consider there to be a target on their forehead that Rumplestiltskin is either going to target for extermination or submission. So self-preservation is probably a good motivation for anyone not committed to either side. They have no choice, really, unless they can constantly stay out of his reach every waking moment. Once he does get his hands on them, they either bow or die. So he's really giving them no room for not making a decision. It's really only a matter of time before he catches up to them, so unless they're a real coward, they'll figure out what they want to do before he's knocking on their door.