I think as much as NASBA is to blame, all of us are as much responsible for bringing down the site on results nights. I don't know whats the scale of usage of this CPA Exam Result Watch thing, but you know it multiplies the effect, because it hits the NASBA Scores page almost every second (automated) while its running on your computer which is not possible manually unless you are sitting there hitting refresh on your browser literally every second.
I think NASBA should put CAPTCHAs on the scores page as well to disable this and any other such bots. You may disagree, but believe me it may actually solve the problem.