The author's objection in this case is that this was just another question on a worksheet that was graded right or wrong then the class moved on to other things

The author's objection in this case is that this was just another question on a worksheet that was graded right or wrong then the class moved on to other things without further analysis or explanation. Not that the problem was impossible. If the lesson of an "impossible problem" was a deliberate assignment set with an educational intent then there should have been a follow-up or even a primer beforehand so that the "poor kids" are not left thinking that mathematics is just randomly weird and absurd.