Pretty sure Trump understands the use of sarin looks very much like a false flag attack, despite his rhetoric.
I hope he is maneuvering himself into a better bargaining position and not making excuses for a war we don’t need and few want.
Anatoly Karlin has a good rundown on why the attack looks suspicious: This Fishy Smell of Sarin, or Was It Chlorine?
Bottom line is the worst political loser of the sarin attack is almost certainly Assad, so why would he have done it? In like manner, the worst political loser of an attack on Assad will be Donald Trump (for falling for the ruse), so why would he do it?