There are a couple of leaps of logic that you have to make in order to assume that Iraq would ship to Syria, or that Syria would take Iraqi cehmical weapons.
1- Why take used goods when you probably have plenty of your own? Especially something that is; A: Not all that hard to make on your own, B: Not the most transport-friendly of munitions, C: As already noted, of unknown effectiveness, age and compostion, D: Bulky.
2- Why get rid of them in the first place? Just to prove the US wrong? If they thought they were going to use, what help would it have been? Why go through so much trouble?
3- If you thought you might lose, why would chemical weapons be one of the few things you would ship out? I have heard of people pointing to 'increased vehicle activity' on the border, there must be something sinister in them! Well, there may have been, but I would bet it was personal goods more than anything else. Think back to the Gulf War and the 'Highway of Death'. The guys fleeing were taking some miltiary stuff back but a lot of it was loot. When the chips are down basic survival instincts kick in, and if I was a Saddam crony and saw the writing on the wall I would ship out my wife, kids, mistress and all the goods I could get my hands on, not Saddam's WMD.
4- Syria may be ruled by the Baath party but Saddam and Asad hated each other. Think of the Chinese and Soviet communists, after 1960 they almost went to war a few times because the hatred was so deep (there were a few border clashes). The Baath party was merely a label anyways, Hussien was a thug, not a politician. And once anything crossed the border it was Syria's to keep, jsut like the Iraqi jets that fled to Iran in 1991. Iraq did not get any of them back, so why make the same mistake again?
There is just no credible evidence that chemical weapons went from IRaq to Syria, people are just grasping at straws when they claim that the very slim circumstantial evidence points to such a conclusion. And that is on top of the several leaps of faith that you have take in order to make a convincing argument for the Iraqis to do it in the first place. Syria is already a bad guy, they didn't need any Iraqi help getting there.
Leaps of logic - yes, but the theory that Saddam destroyed his inventory requires just as much of a leap.
1) There were a number of convoys of large trucks that traveled from Iraq to Syria just before the invasion. Those have never been explained - could have been personal goods, could have been the treasury, could have been .
2) You said that you thought Saddam would have destroyed them; your point #2 applies as much to that as to shipping them to Syria.
3) Why ship them out? In an attempt to avoid them being found, perhaps as part of a last-ditch attempt to avoid an invasion. To avoid that charge in a post-war trial, which would not be a far-fetched thought to someone like Saddam, considering his escape from justice in 1992
4) Yes - and they also both supported the North Vietnamese, too. Syria and Iraq both hated the U.S., probably more than they hated each other. Assad had plenty of reason to try and assist Saddam.
And again - no evidence, or claims even, that everything was destroyed. Your "no credible evidence" applies just as much to the supposed destruction as it does to the supposed transportation.