I think every company does (or should) have a set procedure for handling such events - much the same as companies have a procedure to handle responsible service of alcohol, smoking on board, disruptive pax...
- if you follow procedure, you cover your own backside, so why not...
- as far as the odd passenger who refuses goes, making reference to the captain and the course of action to be taken if they dont comply usually does the trick - if it dosent, one warning is enough! This is of course dependent on having a team that will support your decision.