I have never even heard of the ACORN Archimedes!! lol
I never saw RiscOS before, and I find no compelling reason to do it now. Perhaps someone who has lots of software for it has such a need. But nowadays people are familiar with Windows (until Win8 came to existence) and with Linux. Both Windows and Linux have lots of free software - a far wider choice, I'd say, than the OS that was extinct for decades. From any practical point of view, this development is not very useful. It may be good from some educational point of view, but I cannot judge that because it may be that someone, somewhere must familiarize himself with this OS to save Earth, or something :-)
But even from the educational POV, offering BASIC for learning when C# and .NET (or Mono) are freely available... that doesn't look like a good advice. R-Pi can be used for learning, but I personally would recommend to learn modern technologies instead of those that failed, decades ago, to survive in the marketplace. If someone walks up to me today and asks "what do I do to learn programming" I would probably recommend to get a PC, an Android phone, and an Android SDK. This is something you can make a difference with.