I think there's a bug in this feature:
A problem setter can disqualify/ rejudge/ set score submissions of problems that he doesn't share the authorship.
This means a problem setter might manipulate any submissions even ones he has no responsibility. Actually, (Some) little evil Psetter(s) is toying with our online judge site and cause a lot of trouble and confusion to users. Hope that this problem will be fixed soon.
I also suggest that when a problem is disqualified or set to a fixed score, its owner should be notified of the execution and executor.