” Use of a nuclear bomb would be suicidal on Iran’s part “
You mean like a suicidal bomber. This is a country that supports suicidal bombers.
Islamic eschatology calls for the arrival of the 12th Iman, who will rule the world in the name of Allah. The Iranian mullahs, unlike Christian dispensationalists, will take action to insure their version of the millennial kingdom. Causing the destruction of their base by attacking the Israelis with one atomic bomb, only to face assured destruction by Israel's retaliation would not bring about the Islamic millennium, but rather break Muslim power for centuries.
Judging by their actions, I don't see the Iranian government as suicidal.