That’s correct - Live Radio is not currently available in ARC. The Live Radio reliability improvements mentioned in the email were for Roon. Sorry for the confusion there - the wording could have been clearer.
Live Radio is something we would like to bring to ARC eventually, but it is a significant piece of functionality and is not something we expect to add in the near future.
Even though we have added quite a bit to ARC over the last six months, including streaming service pages, nugs support, and Focus, we are now refocusing our attention on reliability and performance, similar to what we have been doing with Roon. We are seeing a clear signal that this is what matters most to users right now: new functionality is hard to enjoy when the client itself is not consistently behaving as it should.
Once app is performing as reliably as we believe it should, we will continue expanding what it can do, including Live Radio.