While stopping spies/trolls from pulling tactivators is a more complex issue, I Have also noticed lots of new players to wvw will often see these and be like "Hit F to pull, I wonder what this does?!" and bye bye emergency way point. My suggestion is maybe add an extra dialog box before letting a player pull a tactivator for the first time.
For example something like, "tactivators can provide key defenses for the mists battles. If you are not sure what this does, maybe best to leave it alone."
This will let new players know maybe I should think before pulling this, as at the moment it is not clear whether it is to give the player a slight movement speed buff like a shrine or if it is there to be used at key moments.
Also some tactivators like structural invulnerability, chilling fog and others that only are useful if a structure is being actively attacked, should only be able to be pulled if the structure is contested. This may further help accidental pulling of tactivators while making it slightly harder for a spy to pull it in advance of an attack
Full Counter is supposed to counter everything, why else is it called FULL Counter... Just like 100 blades should really hit 100 times so you instantly die to retaliation.