At a glance, my first draft would be like this:
Both parties are acting within the rules of the game, so we're not talking punishments.
Nadrolski is using a Mur-spell accessible to several players, which is limited to being used on people who abuse shared items in any way. Mur claimed that he'd specify abuse cases, but didn't, so we'll have to work off what we have.
Abuse cases laid out by Mur so far are a) having more than one of the same type, b) hoarding on an alt. Starting from there, his intentions seem to go towards using legislatior items to make sure that the items remain accessible to a number of people, where the 'number of people' is defined by the number of items he's providing for each type. I'd think that the factor 'availabilty of the items' needs to be differentiated from the factor 'availabilty of resources', as Mur has stated several times that depletion of resources is something he wants to have in game.
Thus, taking several items of one type out of the game on one account is definitely an abuse. I'd even argue that having more than one of a type on one person is an abuse, since Mur made it clear that he doesn't want hoarding on alts, and neither having more than one on an account. Taking that to a stretch, we could argue whether it's hoarding to have one item on one account, and another of the same type on an alt (which i'd agree to if i had to), but one item per person per rotation is definitely not an abuse case Mur had in mind.
The argument of Nad has merit as well, since depletion of a resource means that other people can't use their items while they have it. It makes no difference to a player whether he has no bucket, or whether he has a bucket, but no options to use it, the result is the same: no water dowsed. However, there are several instances when Mur has laid out that he doesn't intend for people to be able to use their stuff too easily, specifically in relation to resources. For example, he's made cauldrons team-based, and set up big stacks of resources in remote locations, both making it harder to use your resources. So, i think we can safely say that Mur didn't mean for depletion of resources to be a case of abuse by default. On the other hand, since the interpretation of Mur's rules leads to making items available to people, and having an item available, but un-usable would be pointless, we can also safely say that depleting all places at all times is an abusive practice.
That leaves the grey zone of abuse between those two: Depleting one location is acceptable, depleting them all is not. So, from my point of view, it boils down to the question how badly darkraptor depleted Marind Bell, and that's something i don't know as of yet, and it might be that his first use of the legislator item was justified. However, it seems that nad banned darkraptor from the buckets for 2 consecutive weeks, and it's simply not possible for dark to do something abusive with a shared item while he's locked out of said shared item. Granted, Mur talks about guarding the items from abuse, but if each case of abuse was enough to preventively lock out people for a prolonged period of time, there would be no way for them to rehabilitate, so that seems to be taking it too far.
So, without judgement on the lockout dark posted about on july 21, the lockout he posted about on july 29 seems unreasonable, and unless there's proof of dark doing something abusive with MB's water resources between july 21 and july 29, i'd be highly inclined to rule in favor of darkraptor for that one.
Again, that's draft version, without looking for specific MB rules (i actually don't even know if such exist) and without getting evidence from either side. If you want a case specific, 'final' ruling, it'd take some evidence, and i'd need to check for all the specific rules.
[Also, in case you didn't notice: If nad depletes resources or not might be a psychological factor, but it doesn't make a difference to how he uses his legislator stuff.]