If that's what happened (remember, we're going off of preliminary reports, eyewitnesses, and the like right now, nothing you here is reliable), then yes there was likely no other outcome.
I doubt it was that calculated, if antifa had people so dedicated to the cause that they're willing to kill and die for it, they wouldn't be expending them in order to kill some random no name right winger. This guy probably did something really, really stupid in the heat of the moment, ran, and then when confronted his existing anti-cop paranoia lead him to panic and do something stupid again.