There's another line of thought that annihilation of one species is most likely by accident, like for example the demolition of a planet to make way for a hyperspace bypass.
For a more practical example, when a Type 2 suffers an industrial accident like a reactor meltdown, it would be indistinguishable from a supernova. If it happens within 1000 light years of us, we'd be just as dead.
We can only take comfort that such an event would wipe out their own civilization, and they have adequate safeties in place as a result.
Oh, and hopefully there isn't a galactic wide cold-war-esque standoff on the possession and use of supernova-creating bombs.
Either way there is reason for fear.