Earlier quoted context omitted.
This is a common feature of dictatorships: a boneheaded decision from a central government wreaks havoc on the people in the field that would know better. It reminds me of Mao ordering all sparrows be killed because they eat agriculture seeds. This of course caused a much bigger crisis with insects destroying crops - because everyone knows sparrows also eat lots of insects.
Sri Lanka is not a dictatorship. They have regular elections. The Rajapakshas might have been authoritarian, even corrupt. But they won the last election in a landslide. Sri Lankans cannot entirely absolve themselves of blame for repeatedly electing a populist regime.
If you have bigoted populace, it's dead easy to bait them into voting for some immediate emotional relief. Sri Lankan's wanted to have fun watching Tamils and Muslims get hurt, so it wasn't all that hard for some politician to get the people vote for him. The worse thing is they even put up with his bad decisions for the same reasons. And they did this for years.
The population is entirely responsible for this.
As it turns out they ran out of time, there's always that one point after which everything comes melting down.