That they're now a theocracy makes them sincerely calling anyone "satan" an even worse thing to pair with them having nuclear weapons.

Err, "the focus of evil in the modern world" then?

If this was a game of telephone, yours would be the mildest interpretation I can imagine of my conversation went with my coworker, but my main impression from them was the Iranian theocracy sees the US as the actual literal devil incarnated.

President Reagan's rather than mine (hence the quotes).

Ah, ok, I thought you were suggesting what Iran thought of the US, I didn't realise it was an old quote from a famous person.

Looking up the quote, Regan was talking about the USSR? If so I think it may be stronger than that sentiment, but I'm not 100% sure owing (in addition to the previous point about games of telephone) to not having lived through the worst of the Cold War — and the small bit I did live through before the USSR collapsed was entirely in the UK and my experience as a child contained more fear of the IRA than the USSR as the IRA were in the news while the USSR were, (like the Klingons that were a thin analogy for them), only in films and on TV.

The policies of Iranian regime are in the least bit affected by longing for lost democracy.

yes, but regaining democracy is a hard battle. So, when you destroy it in the first time, it is not a surprise that warlords keep getting control of power till by some random fluctuation, the tide changes. In western world, it took almost 300 years for democracy to be stabilized.

US also helped current regime when it first gained power.

Fair point!