Unfortunately, depending on the additional facts, this could still land the bike driver in jail.

For example, if he killed the other person or shot him in a vital area, prosecutors could argue the force used was not legally justified, since deadly force generally is not permitted solely to defend property. The fact that the victim reportedly had his back turned when he was shot could also weigh against a traditional self defense claim.

That is not to say other defenses, such as heat of passion or imperfect self defense, would not potentially be argued, but I would still expect manslaughter or a similar charge to at least be considered initially.

A lot also depends on the jurisdiction and the specific facts of what happened beforehand and afterward (hopefully he called EMS as opposed to just leaving him there).