Its still significant though. the Tour ttts from the Armstrong era may have been long but there have been plenty of short ttts in recent years.
The Giro ttt has been 25km (todays distance) or shorter every year since 2007 apart from 2010 which was a few k longer. And that includes the mega doped 2007 2008 and 2009 giros of course, all of which were strong contenders for the most doped gt of all time prize.
The Vuelta since 2006 has had 5 ttts, all of them 16km or less. In the Armstrong (Heras) era the Vuelta had 3 team time trials, all of them similar lengh to today (24, 28 and 28km respectively)
Also most of those ttts were stage 1 and didnt come after 3 days of racing, a transfer and half the peloton nursing injuries.
Like most team time trials today was a circuit that finished where it started so it cant be explained by wind.
There are other variables to consider like how technical the circuit is, and it would be difficult to make direct comparisons between this and any other specific ttt.
But when you have a sample size of 6 ttts from the giro 8 ttts from the Vuelta, and 1 from the Tour, of this length or shorter from the last decade, and this is by far the fastest one, it does seem to at least offer a peripheral challenge the narrative that things are getting slower.
Even if we assume 2011 Tour was clean, 2011 and 2012 vueltas were clean and 2013 and 2012 giros were clean, this is still faster (and quite a bit) than all 10 ttts of this distance or less from the "doped era". (that cq has recorded since it formed anyway)
Edit: though after checking out the other ttts for myself i find that today actually was not the fastest ttt in history. The 2011 Giro ttt was faster by quite a bit - about 4km/h. All others in the above list however were slower.
Edit2: thanks to cyievel for pointing out that cq had the distance for the ttt that I thought was faster (2011), wrong. It was actually 19.3km not 21.5 and therefore the time of 20.59, nowhere near as outrageous as it first seemed (61.47km/h.)