I tend to agree with Deathwynd. It may not be intentional for planets to be able to be targeted by a wormhole effect, but I rather doubt that it's a bug or exploit that the developers will or should bother fixing. Teleporting planets to random points in the galaxy may be entertaining, but it isn't terribly useful. It's also something which requires the completion of a construction project to perform, which means that the world isn't doing more useful things like building ships and other planetary improvements, conducting research, or generating income. I doubt that the developers intended for planets to be able to do this, but on the other hand it's also unlikely to matter in any significant way. Adding controllable movement to a planet at little cost would be something else, but this isn't anything like that.