Malicious intent is not required in order to be charged and convicted of a crime. Extreme recklessness is sufficient. Consider a driver who gets crazy drunk and then causes a crash that kills someone. The driver had no malicious intent, but engaged in behavior that was so reckless that death or injury of others was likely to occur. That driver would be looking at a manslaughter charge at minimum.
I am not a lawyer and don’t know anything about French law. However, it seems to me rather odd that a spectator can be charged with causing a wreck while contestants aren’t.