This assumes that people arrive at stated preferences rationally (i.e. "I have observed the behavior of Tic Tacs and read some papers on the topic and believe t

This assumes that people arrive at stated preferences rationally (i.e. "I have observed the behavior of Tic Tacs and read some papers on the topic and believe them to not be sentient"). Instead, my intuition is that most of these opinions are a result of emotions ("I find Tic Tacs disgusting and therefore think that I am justified in harming them, but because I'm a good person, this also necessitates that they are not sentient because good people don't harm sentient beings.") So disagreement is not over whether Tic Tacs are sentient, it's that one person finds them disgusting and the other does not. For the person who finds them disgusting, the person who wants Tic Tacs to not be harmed is not just somebody with a different opinion, it's somebody who is now also disgusting because they are arguing for and defending something disgusting. This then justifies negative emotions and negative behavior towards that person (and vice-versa).