This might sound like a good idea, but it has a number of drawbacks from an operational perspective.
Different equipment often requires maintaining slightly different SOE builds for them. If you have a range of different hardware types you will find that the additional labour maintenance costs easily outweighs the saving made in re-purposing the older equipment in a lower demand environment. Bear in mind that today's equipment is heavily commoditized and has a much lower unit cost than 10 years ago.
Older equipment re-repurposed in this way often requires rebuilding or re-imaging. This isn't mentioned in the blog.
Older equipment can have unexpected failures that result in high levels of support time to recover needed information. How many times have you had to recover some one's email archives from a failed local disk because they need them urgently? Or have to suddenly find another PC because the dust in the environment has caused seizure of a cooling fan, wrecking the PC?
These are all more likely to occur in re-purposed older hardware. Believe me. This is a common practice in manufacturing plants.
The cost of lost production can easily wipe out any saving made in minutes. False economy in these situations.