Btw, if the report you're linking to is the same one I read about then it uses highly questionable sources (I think it was MEK operatives, not sure though).
Any claim that HRW is part of a propaganda machine working against Iran is an extraordinary claim, and the onus is on you to back it up with evidence.
It's particularly difficult to have that claim stand on its own when it's so easy to get firsthand narratives of the brutality of the Iranian regime from other sources. It doesn't take MEK spies to reveal the stories of people tortured hung from construction cranes for writing subversive blog posts.
"the onus is on you to back it up with evidence." - funny how that burden never seem to apply to those making the actual accusations. Often someone makes a claim about brutality and it's accepted at face value simply because the accused is somebody we don't like politically.