I would have totally been down for that. But Tomalak never seemed EVIL though. Just someone who was more a rival and adversary of Picard, than an out and out nemesis. I don't see Tomalak wanting to commit genocide. Rather, he seemed more like someone who wanted to beat Picard for the glory of besting a worthy adversary that he has a grudging respect for (whether he admits it or not). Sela, however, just straight up hated Picard's guts and her own human half. I can see her wanting to destroy Earth.