My worries about the LHC are a bit different. I don't think about mini-black-holes. But I think the LHC could resonate with the earth under certain circumstances. The complaints are more like about this machine called haarp: a presumably scientific apparatus could be turned something, that could influence the whole world by modifying the earth fileds. This could be done with remote controle of experiments and two beams that collide in specific rythms, that could be specific to things, areas or even persons.
That should be prevented by random timedelay of experiments or limitation of the power of the LHC and sever monitoring of the remote access.