I'm not so sure what "bump" means

"Bump" means that he's adding a zero-content post to the thread for the sole purpose of making it float back up to the top of the thread list, in hopes of the thread gaining attention again. Usually, when someone does this, their reason for bumping the thread is implied by context and little or no explanation is needed.

I've seen this done as common practice on other BBS's which sort by date, and as long as it's not over-done, and it's done for a good cause, I don't consider it an abuse.