Why didn't they stop him from doing these actions?

https://www.yahoo.com/news/former-secret-officials-says-agents-090958488.html
Former Secret Service officials say agents should've kept Trump low, not fist pumping

After an assassination attempt on Donald Trump by a sniper on Saturday, he stood tall, gave three fist pumps and yelled "Fight, Fight, Fight!" to the crowd before being moved off the stage by his protective detail.

The instantly iconic image struck many supporters as heroic, and it was admiringly referenced by speakers at the Republican National Convention. There's even a Trump-affiliated $299 commemorative sneaker showing his raised fist, bloody face and the words "Fight, Fight, Fight" underneath.

But Trump's extra few minutes on stage were a serious operational failure by the Secret Service that further endangered the lives of the presidential candidate and the agents protecting him, former Secret Service agents and other experts said.

The standard protocol is to keep the "protectee" − in this case Trump − bent over at the waist, with his head down and his body fully surrounded by agents as he is whisked off the stage, to prevent additional shots from hitting him, according to multiple former Secret Service agents.

Why didn't they stop him from doing these actions?
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