Instead, I believe the way he went about it was clumsy to say the least. It created perceptions that were avoidable. It created the impression that he is being whipsawed by events (e.g., the outcome of the Parliamentary vote in the UK) rather than shaping them. He could have gone to Congress first before all but committing to a military response. Had he stated from the onset something along the lines that the U.S. must respond to the crime against humanity that took place in Syria and therefore he is asking Congress for military authorization to maximize his flexibility, things would be different. Instead, he all but declared that the U.S. would be responding militarily and imminently then, in a follow-up address (after the UK Parliamentary vote) stated that he would ask Congress for authorization (taking away the imminence of the response and creating questions as to whether there would be a military response).
In short, the strategy is right. No body can confer the kind of legitimacy the Congress could. However, the tactics were anything but optimal. They led to perceptions that were largely self-inflicted and entirely avoidable.