I've never heard this before. I think that pre Khmer Rouge Cambodia had a tiny graduate population <1% and had no issue of agricultural production apart from the intrinsic vulnerability of subsistence farming to crop failure and famine. The disaster of year 0 was not the result of either external aid or poor education, rather it was a political decision supported by regional powers for geo-political ends.
This is where I took this from
(You can use some translation service)
And it states that most of Pol Pot's cabinet were graduates of universities, more than half of them Sorbonne.
And then it tells about previous ruler investing in education heavily without then caring about employment of graduates, all this on top of population surge.