If there is not a bounty for a BH to chase down then the only thing a BH can do is scan cargo.
If he happends to pass by a pirate ripping a trader he should just make sure to avoid the wreckage and ignore the screaming. I will keep this in mind.
There's actually one other option. Since BH are after money, they might ask traders if they want an escort. If you're just doing it so you can fight the S-13 unlawfuls, then you're still a PvP-whore, but if you charge reasonable fees (like 2 mil for 40 mins or something) for your services and are actually turning a profit its fine.