I'm not sure about that - the NASA commentator says the LES tower was jettisoned pretty much at the time the booster appears to have failed. From her later comment, she doesn't seem to have seen that a failure happened until some time afterwards, even though the Russian's are clearly saying a failure happened, so I think she's reading from a script of what should be happening at that moment. So I would not treat her saying the LES tower jettison occurred as being certain.