The gymnasts that broke leg at Olympics was later dropped while being loaded into an ambulance. This has to be the worst start to an Olympics for any athlete in history. Breaking your leg would be devastation enough; but being dropped by emergency personnel would add insult to injury (both literally and figuratively). Yes, other athletes have been injured during Olympic games; however, few have been injured by emergency personnel as well.
While Samir Ait Said certainly had a terrible go of it at the Olympics, this can't be considered the worst start to an Olympics in history. That unfortunate distinction goes to Georgian Olympic Luge slider Nodar Kumaritashvili, who died after crashing during a practice run on the day of the Opening Ceremony.
This injury is pretty bad, but it isn't as bad as the Greg Louganis injury from the 1988 Seoul Games in 1988. Nothing is quite as messed up as whirling around during a dive and hitting your head on the diving board. I remember seeing it on TV when it happened. I still get a migraine when I think about that. Oh yes, people still play the video on YouTube today.
Yes, what happened to that gymnast was awful. He suffered a horribly broken leg and simultaneously watched years of work and training go out the window. And yes, he was dropped after being injured which was also awful. But to blatantly state that this is the worst start to the Olympics for an athlete ever is assuming a lot and possibly short-changing the experiences of other athletes who also got off to a rocky start or were injured early in competition. Was what happened terrible? Yes. Is it the worst-ever experience for a single Olympic athlete? Until you survey every Olympic athlete, study every injury that occurred, the athlete's career after the injury, and assess each athlete's mental state at the beginning of the games, you cannot assume this accident was the worst thing to ever happen to a single Olympic athlete at or near the start of the games.