Actually he was not ballistic. He was the opposite. The picture below is a two Hellfire missiles under power launched by a Predator drone. The rocket fuel is burning.
The next picture (below) is of a missile in its ballistic trajectory: after the main rocket motor has fully burned. Guidance motors still operate, but the missile is not under power, it is slowing down although it is traveling very fast. From the time the main motor fully burns, the speed of the rocket is slowing and is determined by momentum, gravity, and wind resistance--by the laws of physics. It is flying in a "ballistic" path.
A missile is ballistic when it's flying toward its target after all the propellant has burned. It is coasting.
My friend was describing quite the opposite. The fast rider was under power and had more power than any other rider in the race. If he were actually "ballistic" he would be coasting.
In terms of missiles, a ballistic missile is one that is launched then travels to by coasting at speed over 4,000 mph. It is no longer under power. It's course is corrected by guidance systems.
A car can't be described as ballistic since it is in contact with the ground. It's path is determined by that contact. But if someone took a car trip that was like a missile flight, the car would accelerate to say 500 mph and then coast trip it arrived. That trip would require very level, very straight roads. Both wind resistance and rolling resistance would limit the distance, but it would be possible. The steering wheel would be the guidance system.
Science words, for reasons I don't understand, can enter Pop culture with meanings opposite their scientific meaning.
The most well-known opposite word is Theory. In science, a theory is the BEST possible summary description of a body of research. So the Theory of Universal Gravitation describes the motion of all objects including missiles, both under power and in ballistic flight.
But in Pop Culture, "My Theory" describes nothing more than an opinion with no necessary connection to fact or reality. My Theory could cover things like believing fluoride is a communist plot or that Stanley Kubrik faked the moon landing.