well, eppy, the bounty hunter certainly has the wealth to produce them en masse. The thing is, when you think bounty hunter, you think usually of lone pilots, or band of pilots that says, goes up to 100 people or so, or 100 hunters, soldiers, whatever. They are soldiers of fortune. And certainly if all these guys united themselves together, they certainly can produce battleships. The thing is, I can't see why they would - it's all about a market of competition, lesser number you are, bigger the prize. They are all individualist, coming from the lowest - ex criminals count for an important proportion of their population.
A large BHG coalition could buy battleship, thats right, they'd have plenty of men to man it beside that.
But little clan of 100 men at max, would get you in the range of cruiser and below - but then, I believe 100 is very extravagant like number. more like a 50 maximum.
The thing is, descriptively speaking, I believe logically, it's the merc who should be allowed larger ships, as they could be ex warship crew that has all defected with their ship for instance. But a simple swap of ID restriction is really not the good thing to do.
As to restriction, well, as I said, anyone with a minimum of patience to harvest a billion, has the patience to farm npcs (if guard thingy was your idea as it seems to be the most popular one around). killing npcs wouldn't improve their RP, nor get them to forum.