Oswald didn't have to know SFA other than the prez would be passing by his place of work on the Friday of the week he found out about it. Shooting at Kennedy while still on Houston would be plain dumb, no matter from which trigger-happy-cop-or-hung-over-SAgent-position.
So from your edit of my quote I take it you don’t disagree with the rest.....
"Once the first shot rang out the shooter would logically assume the gig to be up. At that point return fire become a distinct possibility. The longer the duration from the first shot the greater the threat to the shooter."
Am I correct?