I get the point, but analogies always breakdown if you pursue them too far. Syria is entirely about hidden agendas imho. Also a terrorist attack on American soil gives more jobs to the boys and could get the NSA off the hook. It appears it was Assad's brother who ordered the attack. How culpable does that make Assad? The UN was kept out for five days and the area was shelled. Dead people do not protest at all; chemical weapons are clinical and convenient. Still at least Al-Qaeda are being kept off the streets.
And today the UK Government is saying Britain will stand by the US. That's the "not doing anything version" of "standing by", presumably.