Can biotechnology be a bad thing?
You are right to be sceptical of this statement.  Let's take it step by step.

Will developments in biotechnology increase world food production?  Almost certainly yes, provided other things are equal.  But the reality is that other things are not equal.  Climate change is likely, other things being equal to reduce agricultural productivity in some parts of the world. Whether the positive effect of biotechnology will more than offset the negative effect of climate change is unclear.

If world food production increases, will prices of agricultural products fall? Not necessarily.  Demand for food is rising due to rising population and to rising incomes in much of the world. Again, the net effect (of rising supply and rising demand) is unclear.

If agricultural prices fall, could this increase hunger for some people? Yes, this is certainly possible.  Those most at risk would be people in poor countries who have relied on farming for their income and, due to limited education and training and/or location, have limited opportunities for alternative employment or other income sources.  The book is right to imply that hunger is as much due to low incomes as to food supply.  But the argument that the overall effect of biotechnology will be to increase world hunger is unconvincing.