Dennis Ross' tortuous logic

Dennis Ross writes on the Room for Debate blog of the NYT, on the question Saudi support for Egypt:

For the Saudis, there are two strategic threats in the region: Iran and the Muslim Brotherhood. The Saudis back certain opposition forces in Syria to weaken Iran and they support the Egyptian military to undermine the Brotherhood. We will not persuade the Saudis by arguing that the military is overplaying its hand.
If we want to move the Saudis on Egypt, we must address their strategic concerns; meaning, for example, that we must convince them that we are prepared either to change the balance of power in Syria or that we will, in fact, prevent the Iranians from acquiring a nuclear weapons capability.

That sounds more like what Dennis Ross wants the US to do (i.e. more hawkish positions on Iran and Syria) than something that the Saudis would genuinely take into consideration. For if they are concerned about the MB, why would they adjust that concern based on the Iran question? And why should the US decide to shift its positions on Iran simply because of the Egypt question?