I suppose not, it maybe is abusing a system that was added so people could quit the game in mid space when too far away from a station. Its intended use is not to evade attack thats for sure.
If the ship is in danger - in a combat situation - then there is a log out timer. If the ship is "save", then the log out is instantly. SO FD specially designed the log out process in that way to prevent players just logging out in combat. That means, that logging out using the menu in a combat situation is completely within the rules of the game as it is specially designed with that situation in mind.
Logging out via menu isn't an exploit, it isn't abusing a game mechanic, it's simply using the game mechanic in it's intended form.
That said: It's really not the best thing to do. It will just motivate pirates to simply destroy any ship that isn't fast enough to comply to their demands. The result is exactly the opposite of what the OP wants. Logging out of the game while a pirate player tries to help a new player (that's my impression from what the OP wrote) is very counterproductive for the new player.
Edit: Just to make it clear: I'm completely against logging out in a combat situation or in any situation with player interaction for that matter.