The Saudi's do not want Shiite Islam to grow this is true. However, I cannot believe the Saudi Royal family has Jewish blood at all. IF they DO, then they are the worst kind of self-hating Jew I've ever heard of.
Also, Babylonian Jew, when it comes to Arabs vs. Jews...vs. Persians...your reasoning is not sound.
Both Shiites as well as Sunnis hate Israel and wish her destruction. The Saudis might like the idea of a war between Israel and Iran. But this would only be because they would hope that Iran would either destroy Israel outright, or weaken her enough for the Arab nations to flood in and finish the job.
The Saudis peace plan is a non-starter.... They do not want real peace and never have.
All these things have nothing to do with bloodlines and everything to do with the religion known as Islam which cannot stand the fact that there is a faith that will not bow to the Islamic Allah in a region they think of as their own.