Unsure if anything changed in V2.1, but based on previous tests :
Drop ~25% of your Cargo value (everything combined), and they'll give you an appropriate message and cease fire.
So tossing them lots of cheap stuff won't work if you retain >75% of Cargo value in your hold.
Disclaimer :
During tests, I noticed that the new (far more powerful) NPCs still continue firing until their (rather unspecific) Demands are met; that hasn't changed.
That can actually mean that the own Ship is destroyed before the Cargo is physically overboard - simply due to User Interface and Cargo drop rate limitations.
Problem is, that large Trade Ships are quite likely to be unable to jettison the needed amounts of Cargo before they blow up.
It simply takes too long - and i.e. a Type-7 or Type-9 won't ever be able to sustain the firepower of a high-tier Anaconda, Python or even a Wing for that long.
IMHO Pirate archetype NPCs basically need to be changed to cease fire when the Player begins dumping Cargo, indicating cooperative intent.
No point in trying to agree to the (unspecific) demand and keep tossing out Cargo after Cargo, only to find out the Pirate NPCs is still not happy... all while continuing to fire all the time.
Basically the new Meta of modded Super-Weapons on NPCs doesn't allow for that anymore.