But the SNP polled less votes than the non SNP votes.
Well of course, but thats a frankly quite odd argument as nobody was assuming either elections were actual referendums.
The Tories, and indeed the Leave vote across the board was lower than the remain vote in 2019, but we all know it was a big vote to leave the EU.
The SNP now have 3 mandates that are far more comprehensive than what the Tories have achieved in 2019. That is an overwhelming mandate to have another vote. Whatever one's view is of how the vote should go, these are ore points of order than opinions.
I mean just to add in, David Cameron won less seats than the SNP have managed proportionately yet we still had the Brexit vote in 2016. Thats how politics works. He got nowhere near 50% of the vote.