Simple answer: Pirate bugs are wicked awesome.

Because, when a giant bug, wearing a cybernetic eye-patch, weilding two swords crackling-blue with energy, holding two sonic deck-sweepers in a pair of mechanacal backups, strides into the bridge on clanking boots, and his whirring 'grasshopper' replacements, all lit up with exposed fiber-optics, and creaks in a booming electronic whine, in your native tounge, through a reconstructed vox-box:
 "I am here to requazition thiz ship for the chirrldren of the hive of t'Err A'aarr! Saav Yrr Selphz aan relenquizzsh to My Q'ommand!"
You do as he says, because he just looks kewler than you, and that means he wins.

Little more detail:
   Vrusk Trade Houses, and Conglomerates, are frequently economically supportive of those who take on charters of External Logistics Management, under the Identity of thier House Logo's.
   Thusly, Privateering is a respected proffession in the Vrusk systems, and they defend thier rights to support that proffesion all the way to the Council, and even support the rights to issue charters of convenience and marquee, of other governments and sovereign entities.
   Technically (and in simplicity), "a ship of a pirate is but a privateer, caught in the wrong waters alone, and a known privateer without a current charter is a pirate, and no waters 'ere to call of port, save all waters be made her home." (it's poetry it's suposed to play on words.)
   That is to say the only thing to truly distinguish between a pirate and a privateer, is that a pirate has no charter or flag of convenience for her actions, and a privateer conducts trade, smuggleing, and 'piracy', in service to one (or more) entities entitled of issuing the right.

   Piracy is only illegal when it is not Privateering under a letter of marquee, and such an attack is still an act of aggression, but the issuing sovereignity (in theory) takes the blame. A full pirate is rare, and not something that often happens by choise, but rather because ship and crew are no longer welcome by, or feeling very loyal to, any sovereign port. Other reasons and situations historically exist, but this is for a context, in which to place the exceptions to the common. Most pirates historically were concerned with repairing their honour and charter that they might have some land to call home before they died at sea, the caribbean pirates were largely an exception, where as several wanted to set themselves up as sovereignity in a new world, and needed the funds for thier new treasuries. (Pirate Kings)
It is the truly unstable cutthroats, and the Pirate Kings, that so often are made to appear as the common archtype.

   I see Vrusk more apt to take a position of 'loyal legal piracy' for one of the Vrusk planets, but may do so in service of other planets, corporations, criminal organizations, or Pirate Kings, out of the same sense of Social Identity, and from there it is all a title of convenience to call them free traders, privateers, or pirates, based on who is attacking whom at the momment.

Have to say I don't see them as being amoral, just alien moraled.
The Vrusk appear to me to be very concerned with traditions, social values, and therefor would likely have many philosohers, some of which would have established other systems of conduct, code of morality. I do see the idea that thier survival behavior dictates a moral standing of 'take what you need for the survival of community and self.' as being a commonly repeated element in all forms of Vrusk religiosity.

Oh humans!!  We discover a galactic community filled with multiple species of aliens, and the first thing we think about is "how can we have sex with them?".
~ anymoose, somewhere on the net...

so...
if you square a square it becomes a cube...
if you square a cube does it become an octoid?