Dear Frankie,
One trade-off with this trick is that it doesn't look nice on the Quiz navigation block - whenever you hover the mouse on each question number there - you'll see the status of "Not yet answered" or "Answered saved' being displayed with full code as <span style="font-weight:bold; color: #ff0000;">Not yet answered</span> and <span style="font-weight:bold; color: #4CBA00;">Answer saved</span> respectively.
By the way, do you plan to upgrade the 'scroll of death' code for higher versions of Moodle ? I did try to merge your code with Moodle 3.1 but it didn't work.
Kind regards,
Tuan