It's not just a character attack to point out that a glorified blog post pulled that number out of thin air.
It would be silly to ask someone to prove that a made up number is made up. How can I provide evidence for lack of evidence. A more reasonable starting point would be to bring up what evidence does exist for the 40k number and then evaluate that.
If you want to continue believing it, that's your prerogative. I don't have a dog in this fight. I'm just doing my part to counter misinformation from biased sources.
FWIW, the Human Rights Activists in Iran (Virginia-based NGO) puts the figure at 6,488