Well, now that you explain it differently we don't have to agree to disagree. We do in fact agree. :)
If you gave the coder the logic/algorithm behind the code and they coded something else entirely that's a different scenario than you telling simply saying "write a bubble sort". Your example changes from a knowledge quiz to a follow the directions quiz. I would still hope the test was interactive enough to allow for the coder to point out that the interface to the sort could remain the same, but an alternate algorithm would probably be more efficient. And of course, you are then allowed to say "Well, the CTO outlawed quicksort because he doesn't understand it" in order to simulate the very real likelihood that eventually the coder will come across a requirements limitation that is totally arbitrary and maybe even counter-productive. And in such a test, a coder who handed in the wrong sort algorithm would certainly fail.