Hmm not sure what I would do with the 50's. I would hope though that I'm not such a retard to the point that huge bugs like this make it throught beta.
But let's say the building exist. First thing to do once a dev know about this is to stop the leak. By removing the building, the missions to it or something like that.
Then you make a statement saying it was a mistake blah blah, we are sorry but we are removing that way of making easy xp. You then fix it for real in a real patch.
Since this seem to be more of a case of broken mechanics and not really an exploit, I don't think banning them would be a good idea. Depend on the style I guess.
Things like the massive nerfing of xp like it was done really suck for retail too. This kind of stuff NEED to be done in beta really.
Thorbadin
www.starsonata.com