It is a good way of doing a one-off nozzle without tools, sure thing, and the technique has been used in the reprap community for years, there is some problems tough.
Firstly you do not want to clamp the sensitive brass thread on a UM2 nozzle in a drill chuck, and since there is about 20mm sticking out in front of the chuck you can not be sure that it actually rotates around the nozzle center (drill chucks are not precision tools), it will probably wobble a little which leads to a risk of either not finding the center or finding the hole but getting drill wobble = either a too large hole drilled or a broken carbide drill.
This is quite a problem when doing UM2 nozzles since they are quite expensive.
There is also a second problem due to the fact that the UM2 nozzle assembly is hugely unbalanced and will introduce vibrations in itself if your drill setup is not very sturdy.
It would actually be better to do the above technique in reverse, and mounting the round part of the nozzle in the chuck, then it would run closer to true to the drills rotational axis, the problem then is that you do not see what you are doing, but since the internal hole is such a tight fit between a 1/8" drill and the 3.2mm barrel (about 0.025mm slop) you have a better chance at doing it with a good result if you do it carefully, but you would still have the problem with vibrations.
I Stand by that the method i decribe at YouMagine is the better way of doing it if you have access to a lathe or a mill.