Although they are not . They may be the only Zoo or place listed on Zootierliste perhaps but they are not the only holders.
I am
not merely relying on ZTL, actually.
To be blunt, I rather suspect I know more than you about the current captive situation of Eastern Aardwolf in Europe, given my long-standing interest in the species and the fact I've been in correspondence with individuals keeping track of the population on ZIMS for some time - and you *do* have a track record of making wild claims and, when called out on it, insisting you have "sources" which confirm these claims.... for instance, the whole "World of Bears" debacle.
To break things down:
All the Eastern Aardwolf in Europe over the past decade or so came from a handful of imports undertaken by Todd Dalton between 2009 and 2012 - the searchable CITES import database indicates that a total of 13 living individuals arrived, and that there have been no imports since.
In the intervening time, the population has slowly dropped as individuals have died, as no successful (beyond 30 days) breedings have occurred, although I know of three collections which had DNS-breedings.
My sources have confirmed to me that ZIMS now explicitly states there are now only four individuals remaining in Europe, with the other nine all accounted for in one way or another:
1,1 at Zoo Halle
0,1 at Hamerton
1,0 at Hemsley
The 1,0 at Hemsley is listed as having come from a private collection - and only one private collection is listed as having received stock from RSCC, in August 2015. This tallies with the announcement by Park Exotics that they now kept the species in September 2015.
TL;DR: Much as I dearly, dearly wish there *were* more Eastern Aardwolf in European collections, there are not
as such, either your source provided you with incorrect information, or you misinterpreted what they said to you.