You are misinformed. There is evidence to suggest the chemical attacks are a fabrication. True or not, it is hardly paranoid given the evidence and even more a stretch to characterize the argument as a "conspiratorial stance". BTW, every type of geopolitical agenda is conspiratorial. Any one of the so-called alternative explanations you suggest would also be "conspiratorial", by definition. Regardless, a fabrication to advance the US foreign policy agenda is as plausible as any other.
To speak to your other points, the analogy of Obama attacking his own people is a non sequitur. if Obama (or more accurately, his handlers) were attacking we the people with chemical weapons, I for one would seek retribution and justice from those who were truly waging the attack. It would be absurd to launch a counter attack against Obama's political enemies (and many, many innocent civilians as necessary collateral damage), in response to a so-called attack by Obama. So, in short, no. I would not be "begging" to play the role of unconscious pawn in a complicated psyops.
Indefinite detention, torture, and drone strikes are unlawful and indicative of a rogue, illegitimate government. This is exactly the point of this argument, which is central to this discussion.
Incidentally, though the majority has nothing to do with it (we are Republic, not a democracy), the majority of Americans nonetheless oppose intervention in Syria. So you are misinformed on this point as well.
Finally, I wouldn't call the argument a "peacenik" argument. You are confusing the common sense opposition to illegitimate government and war propaganda with something entirely different.