This is an interesting theory. The reason why Esmeralda lives in the end of Disney's Hunchback of Notre Dame.
In my perspective, I think that Esmeralda lives in the end not just because it's a Disney movie, and all Disney heroes and heroines must live to have a happily ever after.
But to give Esmeralda fully agency and bodily autonomy.
While I do think that her living on the end to showcase the real difference between Quasimodo and Frollo is a very interesting and insightful theory, that's not how I see it personally.
The whole theme of Disney's The Hunchback of Notre Dame is "Who is the monster? And who is the man?".
Both Quasimodo and Frollo both objectify Esmeralda in different ways on the spectrum.
Similar to the Madonna-Whore complex.
Quasimodo viewed her as an "angel" who can do no wrong and puts her on a high pedestal.
Meanwhile, Frollo viewed Esmeralda as an "exotic beauty", a "witch", and a "temptress" whose body he not only that he needs to claim, dominate, hurt, and control for himself for extremely creepy, gross, predatory, and disturbing reasons.
But also blames Esmeralda, who did nothing wrong, for his own lustful thoughts, actions, and behavior towards her.
Especially inside the Cathedral.
But in the end, Quasimodo let Esmeralda go, respected her, still chose to be her friend, and supported her relationship with a man (Phoebus) she's genuinely in love with just as much as that man genuinely loves her back.
But Frollo?
He chose to proceed to try to claim Esmeralda as his, and attempting to kill her when she refused his unwanted, creepy, fetishizating, cruel, bigoted, delusional, and lustful advances.
And guess what?
He falls into the fiery pit to his demise for it.