Spraying a thick cloud of exhaust on people next to a road might fit the legal definition of "assault", "reckless driving", "wanton endangerment".
This is not some innocent prank.
As a cyclist, rolling coal is a real and present danger.
That's ... still a pretty big impediment, and countermeasures don't have to be perfect.
Taking someone’s toy away hurts way more than a fine or suspension that can be ignored.
Edit: Also, if you just take the truck and issue a fine, it saves another person from needlessly being turned into a criminal.
We do this for repeat DUI offenders, but you need a car to get around most of America-- so even when suspended or unlicensed, people drive anyway.
At that that point they are both (a) uninsurable and (b) illegally operating, and now have more reasons to flee the scene of an accident than they do to remain. If it's some rich kid perpetrator, there won't even be a manslaughter charge if the victim dies.
All arbitrary license revocation does is make the roads twice as dangerous for everyone else.
Remember, drivers licenses were originally born out of law enforcement complaints that the automobile made their lives so much harder.