Every corner has players of both sides barging into each other so I don't think it realistic to call such minor contact as a foul. Unless the GK is made a special case.since Sa was deliberately barged just prior to the header i would argue he did interfere with the goalkeepers ability to prepare for the header .
Changing the Laws so it is offside to enter the six yard box before the ball would be a creative way of preventing this whole issue.
