Personally, I'm against this idea, too. I see two major cons:
1) A monster like this would probably be in conflict with the rest of the game's content. DoomRL is quite an abstract game (for example, we have a trait that literally gives you ammo out of air). Security officer, on the other hand, is a detailed monster - adding him would break the level of abstraction the rest of the content operates on. Incidentally, I didn't like the inclusion of Pancor Jackhammer into the game as well, for the same reason.
2) Doesn't sound quite doomish enough (which is the reason we don't have assault rifles and the like in the game)
So, in my opinion, such ideas are excellent meat for mods, but do not fit well into vanilla.