I can fully understand your mate losing it when someone tried to run him down. But if he'd kept his cool, you wouldn't now be wondering when the idiot driver will take his revenge. Lashing out at somebody, who has shown a complete disregard for the safety of others, to the point of using their car as a weapon. Could easily end up with the driver doing something more drastic in future.
Presumably the name of you business is on the side of your truck. Maybe but hopefully not, the idiot driver could take it on himself or some of his friends, to slyly do you or your property further damage down the line. Let's face it, he's shown little regard for others' property or the sanctity of life.
It's a sad fact of human life. There are such idiots around and sometimes your path might cross their path. The best thing I've found is to not excapirate the matter. Don't turn your back on such people. For one thing, they may well go for you and often such an action will put the aggressor over the edge. It can be trying being polite to such people but a calm manner diffuses these situation more quickly and more safely. There are some, for whom when faced with another's calm manner, can blow anyway. But if you're not lashing out at someone who was the aggressor, such events tend to end better. And don't damage their property even if they deserve it. If you do, they'll have a reasonably lawful claim against you.
A few pointers to calming the other person/s. Don't cross your arms, don't link your hands behind your back and don't stuff your hands in your pockets. Don't point in their direction or adopt a wide stance. All of these are perceived as indifference or dominating posturing and can quickly lead to an escalation of the situation. Try not to swear at the other person and try not to lash out at them either. If a vehicle/s are involved, try to get the reg. number, description of vehicle and number of other people in the vehicle at the time, (But do it without them noticing.) If there are more than one of them, never let any of them get behind you. If they're friends rather than family, one might verbally engage you, while another starts to wander. Beware the wanderer!
When they've gone or if you feel threatened but safe enough to do so at the time. Ring the police with a brief description of what happened/what is happening; the vehicle details and description of the person/s that faced up to you. If they're still there in front of you and you do contact the police, let them know you are doing so. Don't bluff contacting the police. And if you've contacted the police and they turn up, do not back-down from your original position. Not only will the police then be put at a disadvantage in dealing with the situation as is; but they will be disinclined to help out in future or if the matter goes further. (Remember, you called them and there must have been a reason.) Continue to remain calm while in the presence of the police. If they can see you're the calm one, they'll be on your side. If you lose it, the police are then faced with two warring parties and you're unlikely to come out the victor.