Is there a way to prevent moderators from purging topics / posts and change it to soft-delete topics and posts instead? It'd be a nice precaution incase a moderator account is compromised or a moderator goes rouge.
At this time I don't believe so, you'll need to create some sort of script to automatically execute the privilege removal call and run it on all of the categories.
@MJ I'll just create an issue for you so you don't have to worry about it.
For future reference, though:
You go to https://github.com/nodebb/nodebb/issues and click on "New Issue". If you don't already have an account it will ask you to create one, then you can report an issue.