The first thing I thought of when you posted the question was don't drill all the way through. Then I opened the file and that was exactly what you did . However you did make a play on wording the hole you drilled it turns out was to be threaded to 1/2 13 tpi. meaning depending on which drill tap chart one goes by the hole would have been drilled to approximately 27/64" just keeping the dimensional sizes in simple terms. this should have left .039" on each side after tapping just like your PDF showed the tap would have cut through the sides or it would have deformed the sides outward just a little to leave a couple thou. the only structural integrity left in the taped hole would have been the ribbons of the threads.
yes it can be done I've done it in steel the same way you described then welded along the sides to secure a stud to make an eye bolt