I feel like the underlying issue here isn't per say balance or an in game conundrum. it comes more from, at least what it appears based on all that i have read so far, an OOC problem. not an IC problem or a balance problem, but who is playing them problem.
That being said, i think the issue should be handled in a slightly more reasonable manner. as opposed to removing a cyborg class that is already weak unto itself, because of people abusing it. that just feel like calling water bad and globally banning the consumption of it, because some people have drowned. (PS analogies are my favorite way of trying to get points across.)
To be honest, i think the Chief of security or whoever is in charge of security at the moment, should keep an eye on their secborgs as much as the Ai should. further more, should that borg start 'power gaming' one should A-help it (sorry admins, don't mean to create more work for you). Additionally, if they, as a player are over stepping their boundaries a little bit by ignoring space law because they are cyborg the CoS or whoever is in charge of security should order the borg shut down. as not even borgs are outside of space law. in fact, playing a borg should require the player to be able to obey more rules than usual because not only do they have space laws, but they have their laws as a cyborg to obey.
My final point is, don't remove a job/cyborg class because some people are awful. don't cut off the flower. the power gamers will just switch modules and do something else to abuse their way to the top. you need to go to the root of the problem, and deal with them OOC. if not a ban, a discussion with them about what the problem is so things can run smoothly.
also before i go. i have seen a lot of sec borgs die in my time. granted it isn't 3 years of play time, but i have seen sec borgs get annihilated in combat personally