Disabling all edits is a way of partially shutting down a wiki. It turns into a traditional static website. This is one of the ways of dealing with technology-savy trolls. Ordinary obnoxious people can be banned. (See BanningUsers.) But clever trolls can spoof IP numbers and host names, outwitting any ( GatedCommunity? ) HardSecurity? you might want to use, and SoftSecurity only really works against people in a social context.
Lone crusaders on a mission are rarely affected by peer review, peer pressure, guide posts, and all the other nice things we usually use for nice people.
Therefore, just lock the site and wait a few days or weeks. If your wiki is not that important to you, you'll feel more comfortable shutting down.
For locking this wiki, see Oddmuse:Page_Locking.