While you're factually correct in every respect, most of your comment is an ad hominem attack. Putin's arguments should be considered on their merits, regardless of his, his government's, or his country's character and history.
I don't have a fancy French word to back me up, but I'm going to disagree. His arguments shouldn't be dismissed out of hand due to his history, but they deserve to come under extra scrutiny. The simplest reason being, as a politician, he is doubtless lying by omission about something, and as he is a politician whatever that something is undoubtedly changes the value equation of his arguments.
I think what I'm saying is given his status as a politician, as well as his history in relation to the subject, we have great cause to suspect him of telling half-truths, which must be evaluated before his arguments can truly be.
* The FSA on the other hand is conducting raids to get rifle ammunition.
* There's the obvious issue that the (apparent) sarin attack targeted a neighborhood that was effectively allied with the FSA and that just happened to be a current critical objective for the Syrian military.
* The attack was relatively ambitious, far more than the minimum required to establish chemical weapons signatures or gin up outrage.
* For that matter, sarin is (unlike VX) non-persistent, making an attack at this scale (a) more technically challenging and (b) more deliberately intended to kill; for instance.
* There's the matter of US intelligence that (a) monitored known Syrian sarin stockpiles, which had noted no loss of custody to the FSA, and (b) Syrian military officials planning the actual attack we're discussing.
The argument that this is a false-flag operation by the FSA is not very credible.
* Syrian military was driving back the rebels in this particular neighborhood just fine without the use of chemical weapons. So Assad in light of this decides to use significant amounts of nerve gas on the very day that he invited UN inspectors to come back?
* Who said that the sarin used was stolen by the FSA from government stockpiles? In an earlier bust of a rebel holdout there were nerve gas delivery mechanisms discovered which appeared to have been produced in Saudi Arabia.
* Finally there is the case of German warships who were patrolling the area and intercepting Syrian military communications and recordings of Assad repeatedly forbidding use of chemical weapons.
If you were the guy in charge of those when they got raided, I wouldn't blame you if you were reluctant to inform your superiors that you dropped the ball on that. =P
Having said all that, I must add that there is not enough proof for either point of view and it's exactly the reason why UNSC shouldn't authorize a military operation agains Syria.
As a side note, who benefits the most from the use of chemical weapons and what seemed to be emminent US attack? Looks like it's syrian terrorists, Saudi Arabia, Qatar and the US.
And here is an interesting thought experiment for you: if tomorrow it turns out that it was the terrorist's false-flag op, will the US intervene and wipe out the terrorists in Syria? Because, you know, they crossed the red line by using chemical weapons that are banned throughout the world?
Except this is a political discussion, so the text isn't truly the subject. It is relevant that Putin is a KGB gangster AND that he's claiming the moral high ground AND that he's protecting a Syrian hand-me-down regime's use of chem weapons. The punchline is how badly the US has screwed the pooch post 9/11.