Before everyone gets all spun up on government waste, inefficiency, etc - I'd like to point out that numbers like these are never accurate. (For the record, I work for the feds, in the IT field).
The problem with "The feds have X datacenters" as a metric is that various audits occur at different times and by different auditors. These auditors almost always have differing definitions for what a datacenter actually is.
In one audit, a group can come through and define "Datacenter" as a big room where servers are co-located and services run on behalf of others. They'll find 2 at my center. Then a year later, a different group comes in and defines "Datacenter" as anywhere that more than 5 computers are running and left on all night. They'll find 200 at my center. Yes, this actually happened! The auditors came through dozens of science labs, found project servers sitting in the labs, and labeled each lab a datacenter.
Now here is the trick to why the statistics are complete mush. A normal IT guy would walk through the lab and say "Hey, that server should be in a datacenter!" -- but the auditors make the reverse conclusion. "Hey, this lab is a datacenter".
Yes, there is waste in the federal sphere and we absolutely need to take action to be more efficient at all levels. However, this article is basically pushing a number that came from someones' imagination, and pretending it's meaningful.