Sir
You think they gona shoot them from northern Iran ?
Draw a line from any point in southern Iran and see how missiles fired from Iran at Israel overfly GCC states
You have to draw Great Circle lines, not straight lines on flat maps. There is a relatively small region of Saudi Arabia which would be overflown by ballistic missiles fired from much of Iran, aimed at much of Israel (but note that PAC-3 based in that part of Saudi Arabia could not intercept such missiles: too high, at that point in their flight), but even that part of Saudi Arabia could be missed by missiles fired at northern & central Israel (i.e. where most Israelis live) from northern Iran. Apart from Kuwait, which is in the path of missiles fired from southern Iran towards Israel (but again, only at mid-point unless fired from a small region near the coast, around Bushehr, in which case they'd be in boost phase), the other GCC states are not on any possible route.
I believe you are misinterpreting what was said by Gates, & you are mistaken in the utility of missiles based in GCC countries for intercepting ballistic missiles aimed at Israel.