No there is no about face because there is no face period. This was an impulsive emotional response and he needed to prove he is not Obama. And because he can (that is American way) he did it.
The trigger was the pictures (this is how the west operates a crusading impulse) innocent children dying. The media did its job of emoting so the public approves legal or not. This is how it went with. Bosnia, Kossovo, Iraq and Lybia.  
 It may turn out it was not a Syrian bomb but by then we will move on and start the next embroglio. That is how we operate. We allow emotions  run our foreign relations. Not good  prospects for peace on this Planet. If Russia or China reacted to emotions we sure would have a major war. It is a shame that Canada always falls in line with US no matter how foolish their decisions.