Surely the intended meaning of the question belongs in the discussion?
You’re right, it’s contrived. But I automatically tried to compare lengths too. So it’s a good lesson in making sure that your simplification of the question still does what the question asks.
I'm not convinced that the intended meaning was to consider a rotating reference frame. I think it was simply an oversight that the straight-line answer and the around-a-circle answer aren't the same. A rotating reference frame is one way to explain that oversight, but it isn't the only one.
You’re right, it’s contrived. But I automatically tried to compare lengths too. So it’s a good lesson in making sure that your simplification of the question still does what the question asks.