No doubt it was handled poorly by all involved.
As for the rest of the stuff the Secret Service, FBI, LBJ, etc di or didn’t do, we will never know the reality until all those involved are long dead.
We all understand that most of what was presented in the Warren Report was fiction.
Some theories have more rigor and logic than others. This is one of them. It explains a lot, especially why the Secret Service acted like a bunch of thugs.