Personally, I think the rule about having to announce your intention to rob someone is a lot of crap, but that's just me. The idea that firing a CD at your target and then announce your ransom sounds fair to me. Your intention should be pretty clear after disrupting your targets engines.
As for pirates pirating pirates? Historically, pirates didn't really care for what ship they was pirating, except for the value of the cargo. Now if there would be any privateer-faction out there, let's say they were aligned with Liberty, who'd they target? The answer is simple enough, any ships not under Liberty or allied with Liberty (as long as the target's worth it).
Piracy is a part of the game, I'll live with that..