I think you're misunderstanding the situation here brother... I read a similar argument to this in the Sydney Morning Herald and would have laughed if it wasn't so dangerous.
This is not some mopping up exercise from Assad. This is a quagmire. Yes, Assad is in the ascendancy, but the Americans still have positions in Syria. The Israelis hit Syria a few days ago... they have no interest in an outright Assad victory given the axis with Russia and more importantly Iran and Hezbollah... Neither have the Saudis or the Qataris... the Turks are yet another dimension given the "Kurd" issue... That's without even considering the French, Brits and other western powers chomping at the bit.
I think it's far more likely that one of the other "actors" had more to benefit from this than Assad. Particularly considering the changing of the guard in Washington where we are seeing an influx of ex-CIA and Warhawks like John Boulton entering the fold.
I can't see Assad ordering such an attack unilaterally without Russian permission and Putin is a geopolitical chess player - it doesn't really make any sense at all.
It's a quagmire alright. But not for the reasons you seem to think. The Americans have very narrow objectives related to ISIS as do the West. This is a quagmire because you have multiple actors with differing objectives.
America/West - ISIS
Russia - aiding an ally and ensuring the Assad regime which permits Russia access to a naval port in the Mediterranean
Iran - I think this is so obvious it's almost not even worth pointing out. Shia ascendancy. Always remember that the Middle East has been controlled for generations by either the Turks or the Iranians. The Saudis are... children
Turkey - preventing the creation of a Kurdish State
Israel - preventing Iranian encirclement (an objective which is similar to Saudi/Sunni concerns)
Sunnis (Saudis/UAE etc) - preventing Iranian/Shia encirclement
Kurds - fighting ISIS, Assad and hoping that their alliance with the West will result in more support for the creation of a Kurdish State
The simple fact is that the West is going to do everything they can to avoid getting stuck in Syria. They will tolerate the continued existence of the Assad regime if it results in stability of some sort that stops the continued outflow of refugees which continues to destabilise Europe. This has become an objective as important as the elimination of ISIS.
If you think the West has designs of removing Assad you're mis-reading the situation. As Trump correctly states the US has spent over $7trn in the Middle East in the last 2 decades. They don't have the appetite mate. They don't fear Russia maintaining a base in Syria as they remain confident of their overwhelming military superiority. Quite frankly that's a return to a status quo that's been in place for decades.
The greater concern would be Israel and the Sunnis. If there is any realistic false flag operation it would have been done by Israel or the Sunnis. The simple fact is that the Israel would simply not bother doing something like that. The risk reward of such an action would be terrible for them. The risk reward makes far more sense for Sunnis to do this, but frankly they don't have enough assets on ground for this to be a possibility. I think you've been reading too many Mitch Rapp books mate, if you think that stuff has actually happened. You need the proper military infrastructure to be able to do this type of stuff and the only beneficiary from this is actually Assad. You keep thinking in terms of global public opinion, but that's utterly meaningless in this environment. Quite frankly I rather suspect that deep down the West is looking at this and saying hurry up and stabilise the situation there so we can get the hell out, and this refugee crisis can end. And as for Assad seeking Putin's permission, give me a break. Assad knows that it is in the vital military interests of Russia to ensure that he specifically survives.
That's geopolitical chess