Okay. The pirate world keeps in mind that if you're either a predator, prey, or competition. If this was Liberty Rogues telling generic pirates (I'm going to ignore the term 'indy' here, it means nothing as this situation applies fully with or without factions) 'get off our turf' that would be fine and dandy. Rule people might argue about it, but at the end of the day it's sound RP.
But then, the Blood Dragons aren't pirates. This Junker wasn't a pirate either. He was a trader.
So, trader goes into system owned by faction x. Pirate goes 'oh look, prey'. Faction x wonders about kicking out trader and pirate. Pirate has free reign to accost the trader. Faction x, being on home ground, can say 'not on our turf mate' and kick out the pirate, or say 'not through our turf mate' and demand the trader drops cargo, or both. In the specific case of Chugoku, I would say both would be appropriate. Blood Dragons are still traditionalist Kusari people- it's who holds the robe and scepter that bothers them, not the way they are used. Traditionalist Kusari people hate foreigners, and "Hulk" and "Dave" are both foreigners. So, get off our turf seems reasonable.
In rules context, if Adv. Trains with Junker IDs can't be taxed, that ID will be whored more than Zoner IDs for power-traders. For generic IDs, the location is immaterial rules-wise. Your backstory sets your personal code of conduct, but rules-wise a generic pirate can pirate wherever he wants. This doesn't mean it is against the Blood Dragons' rules, and they can blow him up if he doesn't leave should they so choose. Faction rules != server rules.
So, to recap, Hulk can pirate Dave free of sanction. The Blood Dragons can also politely say to Hulk "Leave now or you will never leave." The Blood Dragons can also say to Dave "Ahem. Drop the cargo and get out of our sight." No rules broken, although Hulk should have known a bit better than to ply his trade in a system that doesn't appreciate foreigners. Mayhaps I can convince the HG to offer a little bounty on Hulk to get the picture across. In case it still hasn't sunk in, Hulk's actions are punishable by roleplay not by banhammer.