star trek - Why did Ceti Alpha VI explode?

The odds against a planetary collusion in a system old enough to have multi celled life on one of the planets, are well - astronomical.

Planetary collisions are the type of crazy stuff which happens in young solar systems. But in the first few hundred million years bodies in unstable orbits are removed, spiraling inward and being adsorbed by the sun, or spiraling outward and being ejected from the solar system. And sometimes they collide with other planets and protoplanets when on their way in or out. After all the bodies in unstable orbits are removed that way in the first few hundred million years, the odd against any more planetary collisions are astronomical.

It took billions of years for multi-celled plants and animals to evolve on earth, so the Ceti eels prove that the Ceti Alpha system was billions of years old and thus the odds against any planets colliding and exploding would be astronomical.

But that would still be more more likely to happen than a planet exploding from internal forces. Exploding as a result of a collision would be more likely than exploding from internal forces by an amount that would also be - astronomical