Cool defeat but it has been around for 30 years. There are other ways to trick them too.
If you are at an unknown door, you can scan the edge of the frame for this type of sensor. If it is just a reed switch then it is fairly easy to overcome, all you have to do is copy what the magnet is doing. It matters not if it is a NO or NC, just copy the magnet. If it is a balanced 3 reed switch (with tamper) then you will need a little extra info on the sensor. Again, the quickest way would be to scan it while unalarmed, or even maybe through the outside of the door (like with the single reed switches). Replicating polarity and field strength are the keys.
I would be surprised if all of the 3 switch balanced sensors from a particular manufacturer were configured the same. So his defeat stick would only work on an unklnown sensor if that were the case.