I don’t think their comment was pro-Iranian-post-revolutionary-government.

I don't have the confidence you do. I don't remember if this specific tankie has expressed this view before, but I have seen and argued with many tankies who are outright supportive of the Islamic Republic.

US-backed governments don’t typically fall to revolutions,

You sure about that? I can name quite a few.

It’s generally accepted that what came after the revolution was worse, but it’s not just nutters, Stalinists and tankies that recognise it was also bad before, and got that way because the British wanted oil.

The Shah was, of course, awful. He was a murderer, an authoritarian who squandered his nation's wealth, and had no one to blame for his fall but himself and his own tyrannical, torturing regime.

But coming in on a post which is about "Theocracy can reverse women's rights quickly" and putting it down to propaganda of the Shah is, itself, nuts. It's beyond a whataboutism, it's downright deflection and borderline denialism.