If you want to add everything about Metastasis on this map, wouldn't it better to just play Metastasis? You're always comparing Metastasis to this map...
They're two different maps, with their unique features. If you prefer Metastasis, then play it.
Anyway...
Although a rather "free" AI certainly sounds fun, the AI must have some kind of objective. Even if is something liberal...
Though I can't think on a "liberal" objective for the AI, besides executing threats, meaning his mission would be to take down Parasite and TKers. The only way that it would really be effective would be to change the victory conditions, and that anyone that actually KILLS someone (killing the wounded corpse) would "turn" evil and completely on its own. His objective turns instead to kill everything on that station, as well as the humans and the AI must kill him besides the Parasite. Meaning the game could continue after the Parasite is killed.
Could be a really interesting kind of gameplay. Although it would be REALLY chaotic if a bunch of TKers (or in roleplaying terms, psycopaths) enter a Parasite 3 room (are sent together to a lone station.)
So chaotic that it turns out funny. Hehe.