will that possession or alleged possession justify, let say, Syria to carry on a preemptive strike against Israel?
No.
And, since Syria is still at war with Israel, (I believe), and still dedicated to the destruction of Israel, there are only two things preventing Syria from launching just such an attack:
[1] Lack of capability.
[2] Fear of consequences.
By taking down Saddam, we increase the time period for number 1, and add to number 2.
IF Saddam were boxed, I would agree with you. But he isn't. He, and many other lunatics/despots in the Arab world have simply learned the fine are of public relations.
Examples:
1. As you cited, Saddam no longer publicly threatens to destroy Israel. Has he changed his mind? I don't think so. He has merely learned to keep his mouth shut until he gains the MEANS to destroy Israel. Then we will hear from him, but it will be too late to do anything about it.
2. Arafat regularly denounces homicide bombings -- in English -- then praises them and promises the destruction of Israel -- in Arabic. Which head of the serpent do you believe?
3. Saudi Arabia pretends to be our ally, yet {a} its schools teach virulent anti-US, anti-jew, anti-western, and anti-Israeli propaganda to all of its children at every age, {b} it exports its sick, bizarre, and, most important, imperialistic, Wahabbist-Islam all over the world, all the while spending unknown millions of dollars per year on lobbyists and PR firms here in the US to prevent people from knowing what they are really all about.
You are absolutely right about one thing. Bush Senior should have killed Saddam the first time around. But he didn't, and now Shrub has the opportunity to make up for his father's mistake.