

It was a joke. We have invented fission and fusion, but the reactors are still attached it to a Rankine Cycle.
Also, the radius would be considerably larger than the sun. Perhaps not encapsulating The Earth, but that seems like a potential death sentence, if we built a Dyson Sphere rather than a Dyson Swarm
For those that didn’t see the animated series
https://youtu.be/G56VgsLfKY4