He commissioned a poll, with a reputable polling company. He reported on the results of that poll.
That's not a "wagon". It's not propaganda. Read it, don't read it, believe it or not. Carry on insulting him, I doubt he's reading, or would care much if he did.
But he does have a wide readership, and his readers are at least inclined to believe him. Those readers have friends, families, workmates. They're voters, and they're already politically motivated. They can apply pressure to the SNP Scottish Government via their MSPs to have a rethink, or even just a think, since they don't seem to have done much of that.
They can help stop this.
What possible dodgy motive could a male-identifying man in Bristol have, for wanting to influence the GRA in Scotland? That grateful Scottish radfems will throw themselves at him in gratitude?