It is not bad written plot device only the evil will of Alice. Get over it
its a lazy and bad written plot device, muh corruption such blackmail meh, it was unnecessary, one of the most defining trait Lisa have during the game is her "curiosity" towards sex, she was even willing to have anal sex in from of her,
you can get her(them) into voyeurism, or inviting Alice to the sex lessons, or BDSM as well, since Lisa like being dominated and Alice showed hint of wanting to try domination you could allow them to explore that route slowly and let max watch,
all those possible routes+ all of those that i am missing, and what we got was a shitty blackmail