The assassination and the shooting of Tippit only happened one way, there's only one explanation, a single story line or narrative. How many explanations should be given? Five? Ten? The same old delusional lone nutters can't make things up, use the assassination as a grievance event against "the government" or "the CIA" or whatever monsters in their heads they have. We have one and only one explanation. Oswald took his rifle - you really think it was his lunch? - and shot JFK. Then, leaving the scene shortly after - he wasn't interested at all in what happened? - he then shot Tippit. If that's boring then never mind.
Anyway, if someone doesn't believe the 8-10 witnesses who saw Oswald shoot Tippit or leave the scene (and the other physical and circumstantial evidence) I doubt you'd accept witnesses who saw Oswald go down the stairs. And if powerful evil groups did pull this off you can be damned sure they would make Norman and Jarman and others say they saw that very same thing, Oswald going down the steps. If you believe all of this other evidence was manufactured why wouldn't they do something this simple? There I go, boring stuff again.
This is the guy they had to silence, the guy who could expose their plot. This is what they let him do. Meet with his family, a lawyer, make phone calls. And this. If you believe this is what they would allow happen, this is what they would allow him to do, the word delusional does come to mind.