Building a dyson sphere around the sun would kill us just as effectively as using a bioweapon.

With the amount of energy such a system has available to itstelf and the intelligence it has to control to handle all of this, giving a little bit of energy to its personal zoo on the 3th planet might be a no brainer?

Lets hope :D

Dyson spheres are impossible, more or less. There's no physically possible material strong enough to build one. There are wildly impractical ideas like dynamic stability with constant thrust using the radiation from the star, but swarms (basically tons of sun-orbiting satellites) are orders of magnitude more practical.

It would take trillions upon trillions of sun-orbiting satellites in the same orbital plane as Earth to make much of a difference to us, and all you'd have to do to make zero difference is slightly tilt that orbital plane so they aren't between the Sun and the Earth most of the time.

Almost all of the Sun's energy radiates into interstellar space. The amount caught by Earth is a tiny rounding error.

Space is so big. Once you've grasped how big space is, consider that you probably have not in fact grasped how big space is. It's very, very big. It's called space for a reason. I called Earth a dust particle but that's actually generous.

Here is the solar system to scale:

https://www.joshworth.com/dev/pixelspace/pixelspace_solarsys...