While that may be true from a cost/performance point of view, the point of the Talos is to keep the system as transparent as possible (schematics, open source firmware etc.).
If that is not a concern for you it doesn't matter I guess.
But for some people it is, and the Talos is the most attractive board out there from a performance point of view if that kind of transparency is a thing for you.
The customers picking up Talos II boards won't be interested until you can show them a threadripper/epyc system with coreboot.
IIRC some of the latest AMD boards to end up with coreboot support is using opterons from 2011-2013.
I don't think you understand the point of the talos
When did they make Threadripper open source?
Neither processor is open source
Precisely. Since there's no equivalent of the Power ISA in "x86 land", it's hard to make a direct comparison (I don't believe that formally Intel or AMD consider themselves to share an architecture, and they both have slightly different instruction sets), but the closest comparison would be if AMD or Intel released the source code for PSP or ME respectively, along with all other ancillary firmware and documentation for the bring-up procedures so that, without an NDA or business agreement, a third party could design a motherboard around a Threadripper or Xeon CPU, provide that to a customer, and allow the customer to make modifications to the firmware running on that motherboard.