Exploit = to take advantage of. There is a bug with the game lobby that causes it to crash from time to time on exit or boot. Apparently, there is way to do this intentionally. Hence, this is an exploit. Exploit does not necessarily mean cheating.
You should pick up a dictionary some time. It has all sorts of useful info like this!
I'm frankly surprised you haven't seen it yourself. There are several hosts that simply ask people to leave instead of booting them because they are aware of the random lobby crash that can occur when a host boots someone. I have no doubt that there are plenty of people who can attest to seeing this themselves.
It is, obviously, difficult to reproduce because it is intermittent, but it does occur, and it is a problem.
