The Importance field is access-controlled such that (in Ubuntu) only the ubuntu-qa team can change its value. This is useful to stop inexperienced bug triagers from making a mess. However, inconsistently, we appear to allow anyone to change the value of the Status field. Now, it's certainly useful for anyone to be able to set bugs to Confirmed or whatever when enough information is present. The problem is that anyone can set a bug to Invalid, Won't Fix, or Fix Released, which has the effect of removing the bug from default searches. This is at least as harmful as incorrect changes to the Importance field, since it can cause valid bugs to get lost if the bug contacts aren't paying detailed attention to their bugmail.
In particular, we have a novice Ubuntu bug triager who has set a number of bugs to Fix Released lately with no justification and very little accuracy (he doesn't really understand the difference between Fix Committed and Fix Released, he doesn't understand the stable release updates process, and he seems to think that if a bug is old enough then it must be fixed by now). He isn't in the ubuntu-qa team, and my opinion is that he should not be allowed to set the Status field to values that cause bugs effectively to disappear.
personally, i'd say that that person needs to be spoken to, given a chance to change, and made sure what they understand what they're doing. If they keep doing it,
If they don't improve after this, I suggest one looks at filing a ticket for getting them thrown off launchpad, due to abuse.
Malicious abuse due to idiocy (and no wish to change) is still abuse, and should suffer the normal consequences of this.
Ubuntu may have a code of conduct, but it does not say "be nice to everyone, even people who are deliberately abusing your software, people and/or protocols".
Please don't lock down the whole of launchpad, for a couple of abusing bug triagers. There are better ways to stop them from abusing launchpad.