I would think that a theif that's willing to wrench on your bike to steal components would also be carrying tools and would be willing and able to pry a glued bearing or a blob of wax out of an allen socket. What's to keep them from taking a hacksaw and lopping off the whole top of the seatpost and worrying about getting the hardware off later? Do you think they care about damaging your post? At some point I think you just have to do the best you can to protect your stuff and hope for the best.