Then why does Putin support Ahmanutjob in Iran?
Russia is Saudi Arabia without an Islamist nutjob population - its entire economy depends on resource exports. As long as oil prices stay high, the Russian economy hums, and Putin remains every voter's favorite Russian. Plus - Iran supports Syria, which protects its Christian minority. Note that Christians are allowed to worship in Iran, whereas in Saudi Arabia, even private Christian gatherings are banned and subject to criminal prosecution.
The other factor is probably balance-of-power related. Iran seems to be a major threat to the Gulf countries - until you look at a map and realize that Pakistan, a Sunni country with 2.5x Iran's population and nuclear weapons, enjoys a very close relationship with the gulf countries, which have harbored lots of Pakistani politicians-in-exile. India, another nuclear power, also enjoys a good relationship with the gulf states, given that huge numbers of Indian expats pretty much keep the gulf countries running. Any Iranian invasion of its oil producing neighbors would cut off the flow of expatriate cash and make India very, very unhappy. Then there's Turkey, which is another significant regional power that shares a border with Iran and would not be happy with Iranian control of its Sunni brethren in the gulf countries. Bottom line is that while Uncle Sam is the strongest power by far in the region, there are plenty of regional powers that would stop Iran from getting up to any monkey business.