Survey not Referendum?
Perhaps the mistake is calling it a Referendum, which attaches all the legal and constitutional matters.
Take a page out of Australia's book, where a referendum on Same Sex Marriage would most likely embarrassed both sides of government (as neither really wanted to upset their funding sources by having to adopt SSM as policy) so they are having a "Non mandatory, Non binding 'Survey'" [in formal voting Australia applies a mandatory or be fined for not voting policy]. Whatever the result spin will be applied to ensure that the status quo is maintained.
In Catalonia's case a positive survey result would have been a strong piece of evidence to progress their desires through more formal, and legal, channels. If the survey was against then everyone can go back to being Spanish.
Biting the hand that feeds IT
