Comment Re:Very much not new (Score 2) 27
No, you wouldn't -- at least, not with any sensible topology.
The way it usually works is like this: You present your Wiegand card to the Wiegand reader, some magic RF resonance happens, and a stream of bits is produced on a wire.
At the other end of this wire, buried deep in the bowels of the building, is a computer (embedded or not) which verifies that your bits are the correct bits. If they are correct, it closes a relay that makes the door open, and (optionally) signals the reader to provide feedback to the user (blinking LED, sound, etc). If they are incorrect bits, it doesn't do anything with the door, and (optionally) provides feedback to that effect (in the form of a blinking LED, sound, dumping poison gas).
Getting access to the data lines at the reader does not magically equate to physical access to the building, except in Hollywood movies and horrifyingly-bad installations (whereby the insecure reader itself does the numeric verification, and/or uses its own internal relay controls the door).
IOW, you can pry the reader off of the wall and twist any wires together that you want..and nothing happens at all except perhaps a blown fuse somewhere upstream and a headache for whoever has to clean up your mess.