It can be disabled, but last time we tried it just leads to people making posts that say bump, or Up, or ad;lkfjadl;kj, or other bullshit that does the same thing but also sends new post notifications.
I'm all for trying it again now that we have all new members moderated, but I don't have access to the back end of the site. You'd probably have to send a support ticket to admin.
Can you guys tell who bumps this thread every day? If not, then letting the dummies expose themselves with bump posts seems like the better option. Warn, ban, done.