Of course this is frustrating for non-technical users, but letting it get to you is your own fault. Once I realized MSRT wasn't required with S mode, I just stopped worrying about this message entirely, it's really that simple.
Rob
I find this response a little... off the mark. You may have stopped worrying and people on this thread by definition are technically aware. But the vast majority of S mode users are just presented with an error message with no way out. My wife keeps asking me about its appearance on her Go. I worked in the industry for 44 years and have no way of explaining MSRT and its interaction (or lack of) with S mode to her.
As representing the actual target audience of S mode, I think we're right to keep up the pressure and describe the impact of a non-actionable error.