"In the event of failure, the candidate will be asked to withdraw from the Graduate Program.", How is it different from being fired?
When you withdraw from the program, you can tell people later (in a job interview, social situation etc) that you “decided to withdraw from the program”.
If you are fired you will have the option of either lying (with possible bad consequences if the lie is found out) or telling people “I was fired”.
Which of those sounds better?
In the U.S., and to the extent I understand it, in Canada, funding is slightly and significantly separate from "being allowed to hang around, register for classes, etc.".
Of course, in many STEM fields, the usual expectation is that one _is_funded_ including tuition paid, so long as one is "in good standing" in the grad program. That means passing exams on schedule, doing whatever is prescribed.
Failing qualifying exams (if no repeats are allowed) surely puts one "not in good standing". Almost certainly this would entail loss of funding, and loss of tuition coverage. (Loss of teaching assistant or research assistant jobs, too.)
It might not immediately disqualify you from registering for classes, or from continuing in the graduate program... However, if the program requires that you (eventually?) pass the qualifying exam, and you're not allowed any further attempts after failing... success is impossible.
If the latter is your situation, you probably won't be escorted out of the building by security, but at some point you'll get no more pay, you'll be asked to vacate any office space, and have to pay to register, at best.
The only possible interesting thing is to inquire of your program how to get reinstated... or to be supported by them in trying to move to a lower-tier program that might be happier with you.
In some places, doctoral students aren't actually employees though they have some other position, such as a TA, which can be a separate thing. Your relationship to the university is "student", not "employee". In such systems what you suggest makes perfect sense. You can no longer enroll in courses if you fail comps. Normally a TA job also disappears since student status may be required to hold it, but that would be, administratively and legally, a different thing.
But if you fail comprehensive/qualifying exams, you won't be welcome, generally. You will get no benefit for "hanging around" and there is no path to a degree at that institution.
Some places you get more than one chance to pass, say twice.
In other places, doctoral students are employees of the university or a lab, and in such situations failing and being fired are about the same.