If you logged off before someone could aggress you, you remained in space for a maximum of 15 minutes even if someone aggressed you afterwards. Which generally was not enough time for the hunters to find you and apply enough damage before your ship was removed from space, in case of ratting dreadnoughts.
About that I’m certain, but I also seem to remember that in an even more distant past (around 2009-2010), you could actually not receive a pvp timer at all if you had logged out before getting one. Meaning that logging out was safe even if someone scrammed you two seconds after your logoff. They’d then only have the usual one minute to kill you, or your ship would be safely removed.