From the CoC:
Harassment
We do not tolerate harassment within our community or our games. This is defined as being insulting to any person via obscene, offensive, hateful or inflammatory comments. This also includes the prolonged, extensive, and/or malicious targeting of an individual or group of individuals through Frontier-owned platforms for the purposes of disruption or agitation.
Also look here for some more details:
https://forums.frontier.co.uk/threads/support-update-reiteration-of-player-harassment-rules.237761/
There is a difference between shooting 20 random people or shooting the same person 20 times. The first one is within the rules and the 2nd one can run afoul them. Same as boycotting a system or following a group around with the intend to disrupt their game play. First one no, 2nd high possibility of yes. Note, boycotting a system can be done by both sides. There is a fine line between role-play and targeted harassment. Looking from the outside some self-documented behavior might have crossed or is very close to that line.
How Elite is setup if you shoot a clean ship you are a criminal, simple.