If this is not proof, I don't know what is.
Two policemen with highly professional equipment see the assassin. They target him. Wait for him to shoot. Then they destroy him so that he doesn't squeal.
In the meantime, the public spotted the assassin 3-4 minutes earlier. They shout and call out. They warn the police. The police shrug their shoulders.
One way or another, they will eliminate Trump before November. And Biden's trashing is an indication that they are sure that Trump will be eliminated.
The election (if there is one) will be between Kamala Harris and any weak Republican candidate.