After the truly awful photos that have been posted on MNin the early hours of this morning, which I will never un-see, I think you need to have a different policy for overnight moderation.
The site is big enough and money-making enough to support a better system by now. There really needs to be proper 24 hour IT cover. At the very least, the Night Watch volunteers should be able to call a member of MNHQ who is on call overnight who has the ability to either deal with the issue or shut the whole forum down until it can be dealt with properly by the IT bods in the morning.
It's only been a handful of threads affected this evening, but it could potentially be a major spamming of dozens or even hundreds of threads next time. This site is used in other parts of the world in different time zones where more people risk seeing the grossly disturbing content than a relative handful of us up at 3am in the UK.
The current system relies on posters reporting any offending theads and hoping that a volunteer will pick up the report in good time and hide the thread. This morning one of the threads affected took far too long to be hidden, not that I am blaming an unpaid volunteer for that.