I reserve judgment about the reports concerning the possible intercepted communications. What would be critical are the contents and the context of the communications, if they were intercepted. There would be a difference between President Assad's authorizing the use of such weapons and a military unit independently deciding on their use. Perhaps the President's forthcoming release of information will provide insight into the veracity of those reports, as well as their substance if such communications were intercepted.
The second story you cite, the CBS account, reveals:
Director of National Intelligence James Clapper led off the three-hour White House meeting with detailed analysis of the evidence about the chemical weapons attack, the disposition of victims and what the administration now believes is a near air-tight circumstantial case that the Syrian regime was behind it.
I underlined the selected text. If the Administration is talking about a circumstantial case, that would suggest that even if such communications were intercepted, they do not provide the kind of "smoking gun" that would give certainty to who was responsible for the use of such weapons. Instead, it suggests that if such communications were intercepted, there is a degree of uncertainty involved and that they are being interpreted in a fashion that adds to what is described as a circumstantial case.
Also, the UN investigation should be concluded by Saturday. It will be interesting to see if the findings of the UN team, which was on the ground, support the arguments being made in Washington, London, and Paris. If major gaps exist, that would be an argument for caution. In any case, even if one supports military action in response to a use of chemical weapons, there's no need to rush before the facts are established. Waiting won't give the party or parties responsible time to develop an approach that materially impacts possible U.S.-led military operations.