The free kick could only be given for simulation - can't give a free kick for not retreating as that link says
It shouldn't have been a free kick anyway as the by the time, Alexis "reacted" the ball was out of play. Should have booked Alexis, booked and then red carded Fuchs and restarted play with another throw
Shirley, it is the official's responsibility to make sure Sanchez is the correct distance away from the touch line. If they a happy with Sanchez's position when the throw is taking place then, in that instance, the thrower is guilty of ungentlemanly conduct and should be carded. What Sanchez did was embarrassing and its only achievement was getting the other guy off getting a 2nd yellow card
"Scoring a goal is better than sex" - Whoever said that was sticking it to the wrong woman