I know it's not telling you that you must (or even should) ride round in the left, but it's horrendously dodgy advice to even mention it IMO because otherwise few new riders would think to try it. I can't think of even a situation like
@icowden mentions where "a roundabout is fed by single roads" that turning right by keeping left would be a good idea.
Anyway, there's plenty more where that came from, but I feel more examples would be a distraction from whether you can turn right at a crossroads like in the OP, so I've started a thread to try to summarise what's shoot in the current code at
https://www.cyclechat.net/threads/bad-cycling-advice-in-the-highway-code.262435/