Toobin’s “I don’t mean to be unkind” prefix was premeditated. He concludes the interview with the same “mule” animal comparison. Note that “mule” is used in a smuggling context, although still a dehumanizing reference. “Courier” is the value-free term that was available. He did mean to be unkind.
And what are the chances that David was carrying material from Laura to Glen that came from Snowden that Glen did not already have. Zero.