I’m glad Mr. Trump was able to show energy and vitality at such a moment. Most people (including me!) would still be in shock. However raising his arm for a fist bump was probably something the Secret Service wanted to respectfully ask him to stop doing.
Trump is a spontaneous man in many situations.
That’s often a part of his strength. He trusts his instincts.
One never knows how you will react in such a situation, if it has never happened to you before.