let me begin with:
"this post contains no tasteless K'kree BBQ jokes whatsover"..
followed by my sincere apologies to those whom it offends.{Evil Dr Gee, others)..
the K'kree's habit of forced vegetarianism/ expulsion, or elimination/ extermination is a deplorable one-[agreeing with Rancke].
The K'Kree are a major race, and part of canon so we can discuss their innovations, and ways & means of doing things-[this is a free forum, and we all exercise our rights; & if not all of us, our reason!]
That all said and done, the K'kree have no doubt studied eco system control, and eugenics. they may have developed bio weapons to eradicate and eliminate competitors even in herbivore life forms that might compete or destroy
their food--not just carnivores! (to say nothing of hostile plant life!)
Given their TL, geneering a retro virus to eradicate/ sterilize all females of a species (thus ensuring they die out thru lack of reproduction) is but one manner of doing such a job. Like wise bio research in ways of geneering food plants for themselves, terraforming, they excell at.
One can even postulate clever use of carnivores to rid other ones, then introduce a germ that kills off your natural predator once its eliminated your pests. We humans use some insects this way without a qualm. Why not K'kree, on larger scale?
there are kinder ways to go about the eugenics thing as well--comply, or be sterilized, not just shot out of hand-though, a hasty K'kree might see that as more expedient, the long sighted ones would take the other approach.
Forced sterilization isn't pretty, but it sends a message no sophont could ignore. Subject races...hmm. Seems to me a matter of method we quibble over--look at the Hiver federation, some several hundred races in its make up, the Hiver's calling the shots, Ithklur their armies, Z'atch)sp)their starfaring merchants..by agreement or manipulation each fills a role.
rather insidious when you get right down to it..
I don't take the Vargr as a joke, anymore than I do the K'Kree. Indeed the Hunting nature of the Vargr of the rebellion era [say what you like about the script-its more in character for them to do the attila the Hun thing than not].
back to K'Kree..say what you like, they make potent adversaries in the Traveller universe-then, and now as we head towards the TNE 1248 era.