God.. I don't know how many times I'll say this in my life... When someone is green on YOUR hud and they shouldn't be, it is not THEIR fault if they have the correct tag (which would be Corsair in this case, because I even saw TBH later that day, sporting a Corsair tag), it is YOUR fault they are green. You have Corsairs green, they will show up green. You want them to be red, then make Corsairs red. Role play, don't just go so you can be neutral to everyone. Pirates won't care.
BTW @ Commodore, NovaPG CAN attack your trader because it is a Bs| tagged one. That would be a faction fight, not piracy. If you had NO PC faction tag, the NovaPG wouldn't have been able to do that. But as you were, you were a legitimate target for their lasers. Also, only 1 NovaPG was present to shoot you. The other Talarca was no NovaPG.