The cooler is compatible with Intel sockets 2011v3 and 2066, meaning it supported our standard CPU cooler testing system, which is what we use for all standardized testing. However, most CPU coolers also have AMD AM4 or Intel 115x support but we do not test on those platforms, even though coolers do support them.
Yes, it was designed to also fit Threadripper and we do now have a TR4 system for dedicated TR4 cooler tests, but this cooler was shipped to us for testing a few months ago prior to having the AMD TR4 build.
The base of this cooler also does not fully cover Threadripper, either. It is designed by Arctic to only cover the IHS above the CPU cores below. They illustrate this in one of their images for clarity. (see about 1/3 down the page under "Maximum Performance for Highest-End CPUs")
https://www.arctic.ac/us_en/freezer-33-tr.html