You can say that in generating the conditions that trigger the bug, I have taken the multiple choice question to where it was perhaps not designed to go for sane people, but it is a legitimate use case all the same.
I just created (on Moodle 2.8) a multiple choice question with 28 options (multiple answers allowed). After 26, when it ran out of letters of the alphabet, it used "{" and "|" as the labels after a,..,z.
This is a bug report. Please fix when possible.