I would take it on a case-by-case basis. Sure, some pirates hate the BHG more than anything, but some likely won't engage them unless they get too close for comfort. I would allow it. Then again, I'd also allow BHG to fire on pirates who stray into weapons range, but that doesn't seem to be allowed anymore.
Personally, I'd also say that while the BHG are motivated by greed in most instances, pirates are very afraid that the BHG might go and reveal the JH locations, and are angry at those traitorous Hunter scum for joining the other side.