So this is a silly little moment. (read this because its for future reference)
Luckily you added that last few moments, because what's done in the first 99% of the clip isn't exploiting. Brain cells just turned karts on. That isn't exploiting. Everything that happens in this clip is possible no matter who turned the game on/off. The teleporting is something I really have no ideas on what causes it, but what I do know is that turning the game on has nothing to do with it. A red is 100% allowed to turn the game on without anyone on the bridge.
Lucky for you, the very end shows exactly that, even if it's through silhouettes. There 100% was at least one or two people on that bridge. Seems like they all possibly survived, but by this point you had at least said something about map exploiting, even if it wasn't really specific on how. By this point it's either intentional rule breaking or just being unaware of rules. Either way, it means this gets accepted.