Frankly, I don't understand the legal/Constitutional standing issues well enough to comment on that aspect, but I do have a "What If" scenario rattling around between my ears.
Let's say Saddam had sent Syria his chemical weapons prior to the half-assed "inspections", but Assad had already used those up long ago. He then turned to Iran to replace them, who happily obliged. These most recent gas attacks would have therefore been rooted in Iranian-based WMD's.
Far fetched? Not at all.
And it changes the lens from which we view this single event. Instead of placing the focus on Assad it switches the viewpoint to Iran, and therefore Russia by association. And just for sh*ts and grins, it also ties back to plane loads of cold hard cash supplied by none other than Barack Hussein Obama.
If it were not for history books packed full of similar examples this single event could be viewed as an isolated action not interconnected to much of anything. Horrible, yes, but an isolated action. Which is exactly the way most people seem to be viewing this gas attack, a single action that occurred essentially in a vacuum. But history tells us that is highly unlikely.
Which, for me personally, increases the pucker factor exponentially. For the time being, however, I'll go with the prevailing view and try to ignore those voices in my head.