They don't use the Logout Button on the HUD, they just keep the logout command in their chat window. So they just have to hit the return button on their keyboard, shortly before they get killed.

And wdoc is correct. There are particular fleets and their members exploiting it. In general the greatest Trashtalkers around.

Minimum should be, to get a 5 or 10mins penalty for logout of a PvP.