As far as I can tell, it tends to be difficult to sell completely locked in choices based on personality. There is a delicate balance between attempting to write consistent characters and choosing for the player entirely thus in doing so somewhat diminishing the interactive aspect of IF. Far be it from me to claim this as an objective and hard law or something, just my own observations of CoG’s libraries and the forum. But I have witnessed negative backlash against such a dependency labeling it as the removal of agency that you are concerned about. Whether you give that hypothetical/potential negativity more weight than your vision in its pure form is entirely up to you.
Keep in mind though that in real life 180 decisions are very possible and how you choose to behave from moment to moment does not need to be consistent in any sense whatsoever. I would actually argue to make something more immersive, rather than have a MC be unable to choose certain actions, it would make more sense to have characters around them react/act differently or have events unfold differently if they change their mind/behavior suddenly.