The Turing test lets the examiner have whatever conversation he wants with the machine. So the examiners can ask to solve math problems, recognise shapes, interpret poetry, perform whatever task. It doesn't matter either if the machine fails or succeeds at the task, it matters if it fails or succeeds in a way that is recognisably different from humans. And if some new task comes up that the machine has a hard time with, it is only natural that the examiners are going to ask that particular task. So yes it is completely allowed to move the goalpost in the Turing test, that's why it is a hard and interesting test to pass.
