Jumping on a shark is pure foolishness. 95% of the time it may flee but that 5% it does not you will be in for a world of hurt. You might as well say it's okay to walk around tiger infested jungle because all you have to do is outbluff a tiger. It may work some of the time but you will regret the one time it does not work and you are a tiger's dinner. I've dived with them, fished for them, observed them, read about them and although in general they are not out to eat people for the most part, they can do wicked damage with their mouth and you'd be tempting fate by doing that. I love my gamefish but not enough to risk my life for a little bonefish. A shark eating a bonefish, sad as it may be, is part of nature. Sharks eat bonefish, sharks eat tarpon, sharks eat fish. I've read stories of someone being bitten by a 20 inch spiny dogfish shark he was playing with and required months of surgery to fix his arm and tendons. Imagine what a 4 ft lemon could do to you.
Be that as it may if you want to use that tactic to scare the shark away be my guest. Nature has a way of culling the weak, foolish and stupid of any species lol.