ASAT missiles are only suitable for low earth orbit, you’d need a rocket about the size of a falcon 9 to reach GEO where Intelsat was sitting. Think people might notice that. Wouldn’t need the satellite to be on a suicide mission, could just slap a gun on it like the good old days.
Flares are related to the complex magnetic fields of stars. Since red dwarfs are more compact, I can imagine that the magnetic field also being more compact will result in it being more messy, especially if its strength doesn’t scale with the star’s size. The more chaotic magnetic field would result in more flares/more violent flares.