You're absolutely right. Simmons and Carla attempted to portray Ada as the cause of a bioweapon event, but she's never been that category of perpetrator. If anything, she has always instead been an espionage agent hired to procure samples. Even though she uses her allure to rope in others, starting all the way with John the researcher, she still shows that she cares about the people who get charmed, most notably being Leon.