OTL Iraq invaded Iran in late 1980 following Iran stressing Muslim revolution inside of Iraq, and more over Saddam viewing the Iranians as weak. Such views were hardly new for Iraq, and somewhat rooted in Saddam's military planning and buildup since 1975.
Now WI Saddam, deciding a weak Iran was the best target to strike, and feeling that isolation of the Islamic revolution would secure him support from other nations, decided to invade following the Iranian Hostage Crisis? He need not state his reason to invade, but the timing grants him US support for sure, at the same time the structure of Post Revolutionary Iran is only months old, instead of a year or more with a popular movement behind it.
Now WI Saddam, deciding a weak Iran was the best target to strike, and feeling that isolation of the Islamic revolution would secure him support from other nations, decided to invade following the Iranian Hostage Crisis? He need not state his reason to invade, but the timing grants him US support for sure, at the same time the structure of Post Revolutionary Iran is only months old, instead of a year or more with a popular movement behind it.