This is a classic example of Iacoletti, using shady defense lawyer tactics, showing that he is willing to jump through any hoop to get a double murderer off the hook.
One minute, we cannot be sure that Oswald was even aware that the President had been shot at... and then, in the next minute, Oswald possibly left work early because he didn't believe there was going to be any more work that day because the President had been shot at.
Nice work, Sean Kneringer.
So Oswald knows nothing about the shooting, simply walks out of the building, sees the screaming and yelling and chaos all around, and just decides, "I think I'll go to a movie."
Even shady lawyers wouldn't try to sell that one.
Desperate conspiracy believers? Sure, but not defense lawyers.