I question ur line of reasoning as there were just as much insider selling back in May when the stock was in the 80s.
Based on the above, I cannot wholeheartedly agree that insider selling implies a top in price. Even though Benioff has been selling some shares, he still have more than 11 million shares remaining. So far in August, he has sold less than 5% of his total shares. Seems that if Benioff anticipates a significant drop in price that he would sell more than just 5% of his shares.