The only way for K-types to hold their position other then failure of their objective would be to trick nature.
As you pointed out one could actually starve people which isn't a trick at all it is a failure of the K-types objective.
A more logical way to do it would be the fear of starvation in a time of abundance or change genetics which I am uncomfortable with.
For thousands of years one of governments primary jobs was to keep an extra stock of food for a time of crises. Up until about 20 or 30 years ago every country of the world kept extra stocks of food by keeping their silo's full or nearly full. Today our governments have no incentives for the farmers to keep extra stocks of food for a time of crises. As a result there is very little food stocks for an emergency.
The reason for this seems very simple too me there is no fear of the loss of abundance. K-types that know about this issue thinks of this in a K-type manner and believe governments want people to die. r-types whom are in control see it as there isn't anything to worry.
In other words the r-types have no real fear of the K-types return because abundance is an absolute. They resent us but do not fear us. When they actually feared us they killed us as what they did in the last century.
It is very likely sometime in our life time we will have a small world drought or some other natural or man made disaster and without our food stocks it will kill millions and reset the fear of starvation and the return of the K-types for a time.
To maintain the fear for a long period of time I can not see how that can be done without genetic changes.
I don’t think just perceptions of fear would do it, though, as there is a concrete genetic foundation to ideology, even if it only confers a predisposition. Just tricking nature wouldn’t work. Either nature kills back the r-types through competitive tests of fitness prior to reproduction, or she doesn’t and their more prolific, less adapted models become the predominant form.
The thing is, if the r-type alleles are not actually physically culled or prevented from reproducing, they proliferate faster than K-types, and turn the population r-type, which then triggers the collapse. The problem is r-types would not tolerate a Eugenical program where welfare mothers were prevented from reproducing, as they want everyone to have the same reproductive ability, regardless of fitness or contribution to society. K-types will not tolerate it because we want everyone thrown into the competition and free, so they can endure adverse outcomes if they lose. The problem is, all of us will defer adverse outcomes if possible, so we hold them off, until the r-types grow to the point that we can’t any more, and the adversity overwhelms us all at once.
Not sure if we will ever evolve a facet to our psychology which will allow for a more constant suppression of r-types. I suspect that is what is needed to create the perpetually free society. I will say, the WWII and Korean vets I knew in Martial arts growing up were unusually hardassed. I always saw it as cold ruthlessness, but maybe it was what maintains K-type freedom in a society, and what we will return to as times get tough.