just blow up all the transports
it's not like they pay anyway
:::::)))))))
But in all seriousness, it makes sense. If a transport pays you 5.000.000 credits, and then begins to smacktalk you, you should be able to shove antimatter up his tailpipe or demand additional credits. This isn't being unfair to the trader, it's ruling in the direction of common sense.
For a real life example, it'd be like being mugged at gunpoint in the street, handing over your wallet, and then calling the robber a "[insert large quantity of expletive words, phrases, insults, et cetera]", well... you're definitely not acting under the line of common sense, and certainly putting yourself at risk and at the mercy of the now enraged assailant. That same example holds true in the Discovery universe, and perhaps even more so, given the anonymity and increased power divide between a pirate and his corporate transport prey.
tl;dr it makes sense - if traders are going to be idiots, they should be punished accordingly