The argument was made that the US/UK "installed" the Khomeini regime [...] Fair point, I missed installing or did not read it carefully enough, this was at bes

The argument was made that the US/UK "installed" the Khomeini regime [...] Fair point, I missed installing or did not read it carefully enough, this was at best an unintended consequences. But even without intention, there is still responsibility, at least to some extent. Which is why a multinational coalition under UN authority, which included several other Arab countries, put Saddam back in his place. Sure, even if oil was not involved, the invasion of Kuwait or any other country should generally not be tolerated. I mentioned this just to point out how quickly and in some sense arbitrarily judgments can change, Iran is also a major oil producer and there Hussein got support for the invasion. The 2003 invasion on the other hand was simply a crime.