We could argue all night about the why's and wherefores as to how and when Indy2 was first thought of as a target for the SNP. I'm pretty sure it wasn't just the day after Brexit vote and more like the day after the first vote.
Any how if, as you say, people will continue to campaign regardless (and there can be no doubting here has been a vigorous and pretty consistent campaign since 2014 in Scotland) then where is the value for Spain holding a vote? You can easily imagine them seeing that the Indy vote hear merely emboldened the Separatist movement rather than resolving a long term issue.
So suggesting that may well have a lot to lose and little to gain could be nonsense but I'm still not agreeing that it is