I think so mate, not entirely 100% on that, from what I can gather by the SoA-timetable, I suspect the court-hearing scheduled for 4 June 2018, if the YES vote is achieved, will make it a 'legally binding' outcome as such...
I suspect any 'counter-bid' (IF it's coming) would need to happen at the very least, prior to that date, but if I were a 'rival-bidder', I'm not sure I'd be 'playing with fire' so close to the gas perse, but that, in and of itself, could be the 'bidders' strategy...