AIUI, by the time that photo was taken, Porte already had Clarke's wheel on his bike because there were no Sky team mates around, The Sky rider facing Porte had been called back (which I believe may also be against the rules, although Lemond's team turned round to pace him back in a TdF of many years ago). There was no clear video coverage of the actual incident that I can find but in the live coverage, it was obvious that the Sky riders were a bit confused about what was going on and had sat up and starting looking around.