No there was HPC sku of Windows 2003 and 2008 : https://en.m.wikipedia.org/wiki/Windows_Server_2003#Windows_Compute_Cluster_Server
Microsoft earnestly tried to enter the space with a deployment system, a job scheduler and an MPI implementation. Licenses were quite cheap and they were pushing hard with free consulting and support, but it did not stick.
While the registrar should have made more to understand the situation before acting, it’s important to keep in mind that according to itch.io, the request was not a DMCA takedown but an accusation of “fraud and fishing”. There’s probably a very large legal exposure for a registrar to let criminal website use their service if they are made aware of it, so reducing their liability is probably their highest priority.
BrandShield is inexcusable for using such a claim as a first step.