If they find a legal flaw then they can appeal but it has to be a legal flaw not their opinion.
While I wish that were true, I can't help but disagree. 15 of their 16 points last time were pure nonsense - I think the decision could be 100% watertight, and they could still make up some rubbish to delay it, pulling out on the last day again.
They would not, admittedly, have a case to overturn a 'Yes', but I wouldn't bet against them delaying it all again. The only hope is that without Neighbour and Pepper, they'll decide not to.