Theoretically speaking, a county created laws which limited the growth of their population. A few decades down the road that same countries leadership felt like their aging population was going to weigh too heavily on the countries resources and the lack of younger people in their society doesn't have a way to support the aging population. What options would they then have? By eliminating or reducing the largest demographic of people who use the most while contributing the least to their society, they were then able to secure a brighter future for their county and future generations. Would it be far fetched to think a country would manufacture a virus that targeted elderly and unhealthy individuals to reduce their burden on that society?